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1Tiu chun thit k cu

Tiu chun thit k cu 334

Tiu chun thit k cu 335

Phn 6 - Kt cu thp

6.1. Phm vi

Phn ny bao gm vic thit k cc cu kin, cc mi ni v cc lin kt bng thp dng cho cc kt cu dm cn v dm t hp, cc khung, gin v vm, cc h dy vng v h dy vng, v cc h mt cu kim loi khi c th p dng c.

Cc kt cu dm cong khng c bao gm y.

6.2. Cc nh ngha

M cu Kt cu bn di mt u ca kt cu nhp cu.

Dm - Mt b phn kt cu m chc nng chnh l truyn cc ti trng xung tr, ch yu qua chu un v chu ct. Ni chung, thut ng ny c s dng ch cu kin c lm bng cc thp hnh cn.

Ph hoi do ct khi - S ph hng mt lin kt bn bn bng bng bulng ca cc dm ua ra hoc s ph hng mt lin kt bt k chu ko m b x rch mt phn ca mt tm bn dc theo chu vi ca cc bulng lin kt.

Lin kt bulng - Bulng, ai c v vng m.

Cu kin lin kt tng cng (cn gi l ging ngang) - Mt b phn nhm lin kt tng cng b phn chnh hoc mt phn ca b phn chnh, chng li s chuyn ng nm ngang.

Yu cu va p ca rnh ch V charpy - Nng lng ti thiu yu cu c hp th trong th nghim rnh ch V charpy c tin hnh mt nhit quy nh.

Th nghim rnh ch V Charpy - Th nghim va p tun theo AASHTO T243 (ASTM A673M).

Khong cch trng gia cc bulng - Khong cch gia cc mp ca cc l bulng k nhau.

Khong cch trng bn ngoi ca cc bulng - Khong cch gia mp ca l bulng v u ca b phn.

Ti trng ph hng - Ti trng m mt b phn kt cu hoc kt cu c th chu c ng trc khi s ph hng tr nn r rng.

Tit din c chc - Mt tit din c kh nng pht trin s phn b ng sut do hon ton trong chu un. Kh nng xoay yu cu tun theo cc gi thit phn tch c s dng trong cc iu khc nhau ca phn ny c quy nh bng tha mn mnh khc nhau ca bn cnh v bn bn bng v cc yu cu lin kt tng cng.

Thnh phn - Mt phn cu thnh ca kt cu.

Dm lin hp - Mt dm thp c lin kt vo bn mt cu cho chng cng lm vic di cc tc ng lc nh l mt kt cu nguyn th.

Ct lin hp - Mt b phn kt cu chu nn bao gm hoc cc thp hnh kt cu c bc bng b tng, hoc mt ng thp c c y b tng, c thit k lm vic di cc tc ng lc nh l mt nguyn th.

Ngng mi vi bin khng i - Bin ng sut danh nh m di n th mt chi tit ring bit c th chu ng mt s v hn cc tc ng lp li m khng b ph hy do mi.

Khung ngang - Mt khung gin ngang lin kt cc thnh phn chu un dc k nhau.

Gin cu chy trn - H gin trong ng xe chy ti hoc bn trn mc ca m trn ca gin.

Phn loi chi tit - Nhm cc thnh phn v cc chi tit v c bn c cng mt sc khng mi.

Vch ngn - Mt thnh phn ngang chu un lin kt cc thnh phn chu un theo phng dc k nhau.

mi do vn mo - Cc tc ng mi do cc ng sut ph thng khng c nh lng trong phn tch v thit k in hnh ca cu.

C ly mp ca cc bulng - Khong cch thng gc vi ng lc gia tm ca l v mp ca cu kin.

C ly u ca cc bulng - Khong cch dc theo ng lc gia tm ca l v u ca cu kin.

Khoang bin- on u ca gin hoc dm.

Thanh c tai treo - B phn chu ko vi tit din hnh ch nht v hai u c m rng lin kt cht.

Mi - S bt u v/hoc s lan truyn cc vt nt do s bin i lp li ca ng sut php truyn vi thnh phn chu ko.

Tui th mi thit k - S nm m mt chi tit d kin chu c cc ti trng giao thng gi nh m khng pht sinh nt do mi. Trong pht trin ca Quy trnh ny ly l 100 nm.

Tui th mi - S chu k ng sut lp li dn n s ph hng do mi ca chi tit.

Sc khng mi - Bin ng sut cc i c th chu c m khng ph hng chi tit i vi s chu k quy nh.

Tui th mi hu hn - S chu k ti s ph hng chi tit khi bin ng sut c kh nng xy ra cc i vt qu gii hn mi vi bin khng i.

dai ph hy - S o kh nng ca vt liu hoc cu kin kt cu hp th nng lng m khng b ph hoi, thng thng c xc nh bng th nghim rnh ch V charpy.

FCM - Cu kin ti hn mi t gy - Cu kin chu ko m s ph hng c d kin l do hoc s sp cu, hoc do cu khng cn c kh nng thc hin chc nng ca n.

Chun o ca bulng - Khong cch gia cc ng k ca bulng; khong cch t lng ca mt thp gc hoc thp hnh khc n ng th nht ca cc bulng.

Dm t hp - Thnh phn kt cu m chc nng ch yu l chu un v chu ct di tc dng ca ti trng. Ni chung, thut ng ny c s dng cho cc mt ct c ch to (t hp).

Chiu di thn bulng - Khong cch gia ai c v u bulng.

Bn tip im (Bn nt)- Bn thp c dng lin kt cc thanh ng, thanh xin v thanh ngang ca gin ti tit im khoang gin.

Kt cu nhp gin chy gia- H gin vi ng xe chy t mt cao no gia cc m trn v m di v n loi tr vic s dng h lin kt ngang bin trn.

Dm lai (Dm kt hp) - Dm thp c ch to vi bn bn bng c cng chy do ti thiu quy nh thp hn ca mt hoc c hai bn cnh.

Tc ng phi n hi- iu kin trong s bin dng khng hon ton hi phc lc d b ti trng gy ra bin dng .

S phn b li phi n hi - S phn b li cc hiu ng lc trong mt thnh phn hoc kt cu do cc bin dng phi n hi gy ra ti mt hoc nhiu mt ct.

Khoang bn trong - Phn pha bn trong ca mt thnh phn gin hoc dm.

Ging lin kt - Cc tm hoc thanh lin kt cc thnh phn ca mt b phn.

Thnh phn tng cng ngang (Ging lin kt ngang) - Thnh phn c s dng ring l hoc nh l mt phn ca h tng cng ngang ngn nga s mt n nh khi un dc ca cc thnh phn v/hoc chu ti trng nm ngang.

S on do xon ngang - S mt n nh khi un dc ca mt cu kin ko theo vng ngang v xon.Lp khung - Phn ca khung cng bao gm mt b phn nm ngang v cc ct gia b phn v chn ca khung hoc b phn nm ngang tip sau thp hn.

ng truyn ti trng - Chui cc thnh phn v cc mi ghp qua ti trng c truyn t im gc ti im n ca n.

Mi do ti trng gy ra - Cc tc dng mi do cc ng sut phng m cc thnh phn v cc chi tit c thit k r rng.

Mi hn chu ti dc - Mi hn vi ng sut t song song vi trc dc ca mi hn.

B phn chnh - Bt c b phn no c thit k chu c cc ti trng t ln kt cu.

ng sut ko thc - Tng i s ca hai hoc nhiu ng sut trong s tng l ko.

Mt ct khng c chc - Mt ct c th pht trin cng chy do trong cc cu kin chu nn trc lc bt u s mt n nh un dc cc b, nhng khng th chng li s mt n nh un dc cc b phi n hi cc mc ng bin c yu cu i vi s phn b ng sut do hon ton.

Bn mt cu trc hng (hoc Mt cu bn trc hng)- Mt cu lm bng thp tm c tng cng bng cc sn thp h hoc kn mt di ca tm thp.

vng di hn - Loi tc ng phi n hi trong vng cn lu li mt thnh phn hoc mt h sau khi ti trng c d b.

Bc bulng - Khong cch dc theo ng lc gia cc tm ca cc l k nhau.

Tm - Sn phm cn phng m b dy ln hn 6,0mm.

Khung cng - Ging lin kt ngang gin u hoc ging Vierendeel to s n nh v chu cc ti trng gi v ng t.

Mmen phn phi li - Ni mmen do s chy do gy ra trong thnh phn chu un ca nhp lin tc v c gi cn bng bi cc phn lc ngoi.

S phn phi li cc mmen - Qu trnh do s hnh thnh cc bin dng phi n hi trong cc kt cu lin tc.

ng sut phn phi li - ng sut un do bi mmen phn phi li.

Tnh d - Cht lng ca cu lm cho c kh nng thc hin chc nng thit k trong trng thi b h hi.

B phn d - B phn m s h hng ca n khng gy ra s h hng cu.

Tui th mi yu cu - Tch ca s giao thng xe ti chy trung bnh hng ngy trn mt ln n nhn vi s chu k mi lt xe ti chy qua v tui th thit k tnh bng ngy.

Cu kin ph - B phn khng c thit k chu cc ti trng c bn.

L - Sn phm cn phng m b dy t 0,15mm v 6,0mm.

Xon St. Venant - Mmen xon gy ra cc ng sut ct thun ty trn mt ct ngang hy cn phng.

Bin ng sut - Hiu i s gia cc ng sut cc tr do ti trng i qua.

Khoang ph - Khoang c bn bn bng c tng cng, c chia ra bi mt hoc nhiu np tng cng dc.

Lin kt chng lc - Ging lin kt thng ng ngang gia cc b phn gin.

Cc nhp, dm chy di - H dm m ng xe chy cao thp hn bn cnh trn.

Cc nhp dm chy di - H gin m ng xe chy t gn m di v c h ngang m trn.

Bn lin kt, bn ni - Bn c s dng lin kt cc thnh phn ca mt cu kin.

Vm c thanh ko - Vm m trong lc y ngang ca sn vm do thanh ging ngang chu.

Mi hn chu ti ngang - Mi hn c t ng sut thng gc vi trc dc ca mi hn.

Mt ct hp kiu mng - Mt ct hnh U khng c bn cnh ni chung.

Vm thc - Vm m trong lc y ngang trong sn vm c truyn xung n mng chn vm.

Chiu di khng c lin kt tng cng ngang - Khong cch gia cc im c thanh tng cng chu c s mt n nh khi un dc hoc bin dng ang c nghin cu, ni chung, khong cch gia cc im khoang hoc cc v tr c thanh tng cng.

Xon vnh - Mmen xon gy ra cc ng sut ct v cc ng sut php, v di cc ng sut mt ct ngang khng cn l phng.

Cng chy - ng sut m ti vt liu biu l mt lch gii hn theo quy nh t tnh t l ca ng sut vi ng bin.

Mc ng sut chy - ng sut c xc nh trong th nghim ko khi bin dng t 0,005 mm/ mi mm.

6.3. k hiu

A=hng s phn loi chi tit cu to, vng c bao bi cc tm bn ca mt mt ct hnh hp; vng c bao bng cc ng tim ca cc tm bn ca cc cu kin hnh hp; h s khu nhp (6.6.1.2.6); (6.10.4.2.2a) (6.11.1.2.2)(6.12.2.2.2)

Ab=din tch p mt chiu trn tm bn c cht (mm2); din tch mt ct ngang ca bulng (mm2) (6.8.7.2)(6.13.2.7)

Ac=din tch b tng; din tch bn cnh chu nn (mm2) (6.9.5.1) (6.10.5.1.4b)

Ad.eff=din tch mt ct ngang hiu dng ca mt cu, bao gm cc sn dc (mm2) (6.14.3.3.2).

ADT=lu lng xe ti trung bnh ngy m da trn tui th thit k (3.6.1.4.2)

ADTTsl=ADTT mt ln xe (6.6.1.2.5)

Af=din tch bn cnh truyn ti trng tp trung (mm2) (6.13.7.2)

Afb=din tch bn cnh di (mm2)(6.10.5.4.1b)

Ag=din tch mt ct ngang th ca cu kin chu nn (mm2) (6.8.2.1)

Agn=din tch thc nh nht ca cu kin ngoi chiu di lin kt (mm2)(6.8.2.2)

An=din tch mt ct ngang thc ca cu kin chu ko (mm2)(6.8.2.1)

Ane=din tch thc ca cc cu kin tip nhn ti trng (mm2) (6.8.2.2)

Ao=din tch bao bn trong mt ct hp (6.11.2.1.2a)

Apn=din tch ca cc cu kin nh ra ca sn tng cng ngoi cc ng hn bn bn bng vi bn cnh, nhng khng vt qu mp ca bn cnh (mm2) (6.10.8.2.3)

Ar=din tch ca ct thp dc (mm2); tng din tch ca thp tng cng bn trong phm vi chiu rng hiu dng ca bn cnh (mm2) 6.9.5.1) (6.10.7.4.3) (6.10.5.1.4b)

As=din tch ca thp hnh cn sn; din tch bn mt din tch sn tng cng ngang gia hoc tng din tch mt ct ngang th (mm2) (6.9.4.1)(6.9.5.1)(6.10.3.1.4b)(6.10.8.1.4)

Asc=din tch mt ct ngang ca inh neo chu ct (mm2) (6.10.7.4.4c)

At=din tch bn cnh chu ko ca mt ct thp (mm2) (6.10.3.1.4b) (6.10.3.3.2)

Atf=tng din tch ca c hai bn cnh thp v ct thp dc bn trong phm vi chiu rng bn hu hiu ca mt ct lin hp (mm2) (6.10.4.3.1c)

Atg=din tch nguyn dc theo mt ct chu ng sut ko trong ct khi (mm2) (6.13.4)

Atn=din tch tnh dc theo mt ct chu ng sut ko trong ct khi (mm2) (6.13.4)

Av=din tch mt ct ca ct thp ngang chn vt nt do ct xin (mm2) (6.12.3.1).

Avg=din tch nguyn dc theo mt ct chu ng sut ct trong ct khi (mm2) (6.13.4)

Avn=din tch thc dc theo mt ct chu ng sut ct trong ct khi (mm2)(6.13.4)

Aw=din tch ca bn bn bng ca mt ct thp (mm2)(6.10.3.1.4b)

a=khong cch t tm ca bulng n mp ca tm (mm); khong cch tm n tm gia cc bn cnh ca cc hp k nhau trong mt ct nhiu hp (mm) (6.13.2.10.4)(6.11.1.1.1)

B=hng s lin quan n din tch theo yu cu ca cc np tng cng ngang (6.10.8.1.4)

Br=sc khng p mt (N) (6.10.8.2.3)

b=chiu rng thn ca thanh c tai treo; khong cch t mp ca tm hoc mp ca l khoan n n im ta hoc khong cch gia cc im ta; khong cch tnh gia cc tm;chiu rng ca ng hnh ch nht; chiu dy ton b ca mt ct ngang lin hp ca b tng bc thp hnh trong mt phng un dc; chiu rng hu hiu ca bn, chiu di ca mp khng c chng ca bn tit im; chiu rng ca bn cnh gia cc bn bn bng; chiu rng ca cu kin tm hnh ch nht; khong cch t tim ca bu lng n chn ca mi hn ca phn lin kt (mm) (6.7.6.3) (6.9.4.2) (6.10.7.4.4b) (6.11.1.2.2) (6.12.2.2.2) (6.12.2.3.1) (6.13.2.10.4)

bf=chiu rng ca bn cnh chu nn ca mt ct thp (mm) (6.10.4.1.3)

bfb=chiu rng bn cnh di (mm) (6.10.5.7.1)

=chiu rng nh ra ca cc np tng cng dc (mm) (6.10.8.1.3) (6.11.3.2.1)

b t=chiu rng ca bn cnh chu ko, chiu rng nh ra ca sn tng cng ngang (mm ) (6.10.7.4.4b) (6.10.8.1.2)

bw=chiu rng ca bn cnh di ca mi mp ca bn cnh gi nh chu cc m men gi (mm) (6.10.3.5.1).

C=t s ca ng sut on khi chu ct vi gii hn chy (hoc cng chy) khi chu ct (6.10.6.4)

Cb=h s iu chnh gradient mmen (6.10.4.2.5a)

C1, C2, C3=cc hng s dng cho ct lin hp c quy nh trong Bng 6.9.5.11, (6.9.5.1.1)

c=khong cch t tim ca ct thp dc n b mt gn nht ca cu kin trong mt phng chu un (mm); h s trong vic xc nh bn un (6.11.2.1.3a) (6.12.2.3.1)(6.12.3.1)

Csteel, C3n, Cn=khong bn cnh tnh t cc trc trung ho ca cc mt ct ca ct thp, b tng lin hp di hn v b tng lin hp ngn hn cho n th ngoi cng ca bn cnh chu nn (mm) (6.10.3.1.4a)

D=ng knh ngoi ca ng thp trn; chiu cao bn bng; chiu cao ti a ca khoang ph i vi cc bn bn bng c cc sn tng cng dc; chiu cao thc t ca tm bn bn bng; ng knh ca cht (mm) (6.9.4.2) (6.10.3.1.4b) (6.7.6.2.1) (6.10.8.1.3). (mm2)

D=chiu cao m tm b tng lin hp t ti tr s mmen do l thuyt khi lc ko cc i trong tm b tng thi im ph hu l thuyt (mm) (6.10.4.2.2a) (6.10.4.2.2b)

Dc=chiu cao ca bn bng chu nn (mm) (6.10.6.3)

Dcp=chiu cao ca bn bng chu nn m men do (mm) (6.10.3.1.4b)

Dp=khong cch t nh ca bn ti trc trung ho ca mt ct lin hp m men do; chiu cao bn bng i vi cc bn bng khng c sn tng cng dc hoc chiu cao ti a ca khoang ph i vi cc i vi cc sn tng cng dc (mm) (6.10.4.2.2b) (6.10.8.1.3).

d=chiu cao ca mt ct thp; ng knh bu lng; kch thc danh nh ca lin kt; cht ng knh ca inh neo; chiu cao ca cu kin trong mt phng un; chiu cao ca cu kin trong mt phng ct; ng knh danh nh ca bu lng (mm) (6.10.4.2.2b) (6.10.4.7.2) (6.12.2.3.1) (6.12.3.1) (6.13.2.9).

db=chiu cao ca dm trong khung cng (mm) (6.13.7.2)

dc=chiu cao ca ct trong khung cng (mm) (6.13.7.2)

dn=khong cch t th ngoi ca bn cnh di n trc trung ho ca mt ct lin hp tnh i ngn hn (mm) (6.10.4.3.1b)

do=khong cch ca cc sn tng cng ngang (mm) (6.10.7.3.2)

ds=chiu cao ca mt ct thp (mm) (6.10.9.1)

E=m un n hi ca thp (MPa) (6.9.4.1)

Ec=m un n hi ca b tng (MPa) (6.10.7.4.4c)

FCM=cu kin t gy gii hn (6.6.2)

Fe=sc khng nn danh nh ca cc cu kin lin hp (MPa) (6.9.5.1)

Fexx=cng phn loi ca kim loi hn (MPa) (6.13.3.2.2b)

Fn=sc khng un danh nh v mt ng sut (MPa) (6.10.4)

Fr=sc khng un tnh ton v mt ng sut (MPa) (6.10.3.5.2) (6.10.4)

Fu=cng chu ko nh nht quy nh ca thp, ng sut un trong bn cnh di do cc ti trng tnh ton khc vi gi; cng chu ko nh nht quy nh ca neo inh chu ct (MPa) (6.4.1) (6.10.3.5.2) (6.10.7.4.4c) (6.8.2.1).

Fub=cng chu ko nh nht quy nh ca bu lng (MPa) (6.13.2.7)

Fw=ng sut un ca cc mp ca bn cnh do ti trng gi tnh ton (MPa) (6.10.3.5.2)

Fy=cng chy ca cht; cng chy nh nht quy nh ca thp (MPa) (6.7.6.2.1) (6.8.7.2) (6.8.2.1)

Fyb=cng chy nh nht quy nh ca bn cnh di (MPa) (6.10.4.3.1b)

Fyc=cng chy nh nht quy nh ca bn cnh chu nn (MPa) (6.10.3.1.4b)

Fyce=cng chy hiu dng ca bn cnh chu nn (MPa) (6.10.10.1.2d)

Fyf=cng chy nh nht quy nh ca bn cnh; gi tr cao hn trong s cc cng chy nh nht quy nh ca cc bn cnh (MPa) (6.10.8.2.4b) (6.10.10.2.3)

Fyr=cng chy nh nht quy nh ca cc thanh ct thp dc hoc ngang (MPa) (6.9.5.1) (6.10.3.1.4b)

Fyre=cng chy hiu dng ca ct thp dc (MPa) (8.10.10.1.2d)

Fys=cng chy nh nht quy nh ca sn tng cng (MPa) (6.10.8.1.2)

Fyt=cng chy nh nht quy nh ca bn cnh chu ko (MPa) (6.10.3.1.4b)

Fyte=cng chy hiu dng ca bn cnh chu ko (MPa) (6.10.10.1.2d)

Fyw=cng chy nh nht quy nh ca bn bng (MPa) (6.10.6.4) ( 6.10.3.1.4b)

Fywe=cng chy hiu dng ca bn bng (MPa) (6.10.10.1.2d)

fa=ng sut dc trc do cc ti trng tnh ton (MPa) (6.14.4.2)

fb=ng sut ln nht do cc ti trng tnh ton bao gm s khuych i m men (MPa) (6.14.4.2)

fc=ng sut trong bn cnh chu nn do ti trng tnh ton (MPa) (6.10.2.2)

f(c=cng chu nn nh nht quy nh ca b tng (Mpa) (6.9.5.1)

fcf=ng sut un n hi trong bn cnh chu nn do ti trng thng xuyn khng nhn vi h s v hai ln ti trng gy mi tnh ton (MPa) (6.10.6.3)

ff=ng sut bn cnh n hi gy ra do ti trng tnh ton (MPa) (6.10.10.2.2)

=gi tr nh hn gia cng chy do nh nht quy nh v ng sut do ti trng tnh ton trong mi bn cnh (MPa) (6.10.4.3.1c)

ffr=ng sut bn cnh phn b li (MPa) (6.10.10.2.2)

fg=ng sut dc trc trn ton mt ct mt cu(MPa) (6.10.4.3.3.2)

fsr=bin ng sut un trong ct thp dc trn tr cu (MPa) (6.10.7.4.3)

fu=ng sut bn cnh ln nht khoang trong ang xem xt do ti trng tnh ton (MPa) (6.10.7.3.3b)

fv=ng sut ct xon ln nht trong bn cnh dm hp (MPa) (6.11.2.1.2a)

fvg=ng sut ct trn ton mt ct mt cu (MPa) (6.14.3.3.2)

g=khong cch gia cc ng bu lng (mm) (6.8.3) (6.13.2.6.1c)

H=chiu cao hu hiu ca ng hn (mm) (6.6.1.2.5)

I=m men qun tnh ca mt ct lin hp ngn hn trong cc khu vc chu un dng hoc m men qun tnh ca mt ct lin hp trong cc khu vc chu un m (mm4) (6.10.7.4.1b)

=m men qun tnh ca sn tng cng dc ly i vi mp tip xc vi bn bn bng hoc bn cnh (mm4) (6.10.8.1.3)

Is=m men qun tnh ca sn tng cng dc i vi trc song song vi bn cnh di v y ca sn tng cng; m men qun tnh sn tng cng sn vm (mm4) (6.11.2.1.3a) (6.14.4.2)

It=m men qun tnh ca sn tng cng ngang ly i vi mp tip xc vi bn bn bng cho cc sn tng cng n, hoc i vi gia chiu dy ca bn bn bng cho cc cp sn tng cng (mm4) (6.10.8.1.3)

Iy=m men qun tnh ca mt ct thp i vi trc ng trong mt phng ca bn bn bng ca n; m men qun tnh i vi trc thng gc vi trc chu un (mm4) (6.10.2.1) (6.12.2.2.2)

Iyc=m men qun tnh ca bn cnh chu nn i vi trc thng ng trong mt phng ca bn bn bng (mm4) (6.10.2.1)

IM=mc gia tng ca h s ng theo iu 3.6.2

J=hng s cng chu xon St. Venent (mm4) (6.10.4.2.6a) (6.11.1.2.2)

K=h s chiu di hiu dng trong mt phng mt n nh khi un dc (6.9.3)

Kh=h s kch thc l i vi cc lin kt bu lng (6.13.2.8)

Ks=h s iu kin b mt i vi cc lin kt bu lng (6.13.2.8)

KL/r=h s mnh (6.9.3)

k=h s un ct; khong cch t mt pha ngoi ca bn cnh n chn mi hn gc bn bn bng ca b phn c tng cng; h s mt n nh khi un dc ca tm nh quy nh trong Bng 6.9.4.2-1 (6.10.7.3.3a) (6.11.2.1.3a) (6.13.7.2) (6.9.4.2)

L=chiu di nhp; chiu di ca cu kin (mm)

Lb=chiu di khng ging; khong cch n im ging th nht k bn mt ct yu cu chu cc xoay do (mm) (6.10.4.1.7) (6.10.10.1.1d)

Lc=chiu di ca neo chu ct hnh ch U; khong cch trng gia cc l hoc gia l v u ca cu kin (mm) (6.10.7.4.4c) ( 6.13.2.9)

Lcp=chiu di ca bn tp (mm) ( 6.10.9.1)

Lp= di gii hn ging ngang i vi kh nng chu un b khng ch bi s hnh thnh un do (mm) (6.10.6.4.2.6a)

Lr= di gii hn ging ngang i vi kh nng chu un b khng ch bi s mt n nh khi chu xon ngang phi n hi (mm) (6.10.6.4.2.6a)

LE=hot ti

LFD=thit k theo h s ti trng

LRFD=thit k theo h s ti trng v h s sc khng

=chiu di cu kin khng c ging (mm) (6.8.4)

Mc=mmen ct do ti trng tnh ton trong khung cng (N.mm) (6.13.7.2)

Mcp=mmen tnh ton im pha trong xy ra ng thi vi s un dng ln nht ti mt ct ngang ang nghin cu (N.mm) (6.10.4.2.2a)

Mfb=mmen dc tnh ton tc dng vo dm ngang (N.mm) (6.14.3.4)

Mf

=mmen dc tnh ton tc dng ln bn mt cu do bn truyn cc ti trng bnh xe cho cc dm k bn (N.mm) (6.14.3)

Mft=mmen ngang tnh ton tc dng ln bn mt cu do bn truyn ti trng bnh xe cho cc sn dc k bn (N.mm) (6.14.3.4)

Mh=mmen tnh ton khp do chu cc chuyn v xoay do cn thit to thnh mt c cu ((N.mm) (6.10.11.1.1d) (6.10.10.1.2b)

M

=mmen c gi tr thp hn do ti trng tnh ton mt trong hai u ca chiu di khng c ging (N.mm) (6.10.4.1.7)

Mmax=sc khng un ln nht (N.mm) (6.10.11.2.4d)

Mn=sc khng un danh nh (N.mm) (6.10.4) (6.10.4.2.3)

Mnp=sc khng un danh nh im pha trong (N.mm) (6.10.4.2.2a)

Mp=sc khng mmen do (N.mm) (6.10.5.1.3) (6.10.4.2.2a)

Mpe=sc khng mmen do hiu dng (N.mm) (6.10.10.1.2b)

Mps=sc khng mmen do ca mt ct thp ca cu kin c bc btng (N.mm) (6.12.2.3.1)

Mr=sc khng un tnh ton (N.mm) (6.10.4) (6.10.9.2.1)

Mrb=sc khng mmen tnh ton ca dm ngang (N.mm) (6.14.3.4)

Mrr=sc khng mmen tnh ton ca sn dc (N.mm) (6.14.3.3.2)

Mrt=sc khng mmen tnh ton ca bn mt cu truyn cc ti trng bnh xe cho cc sn k bn (N.mm) (6.14.3.4)

Mrx, Mry=sc khng un tnh ton theo hng X v Y tng ng (N.mm) (6.8.2.3) (6.9.2.2)

Mu=mmen un tnh ton, mmen khoang ln nht do cc ti trng tnh ton (N.mm) (6.10.9.2.1) ( 6.7.6.2.1) (6.10.7.3.3a)

Mur=mmen un cc b tnh ton trong sn dc bn trc hng (N.mm) (6.14.3.3.2)

Mux, Muy=cc mmen un do cc ti trng tnh ton trong hng X hoc y tng ng (N.mm) (6.8.2.3) (6.9.2.2)

Mw=mmen ngang ln nht trong bn cnh di do ti trng gi tnh ton (N.mm) (6.10.3.7.4)

My=sc khng mmen chy; mmen chy khi s chy bn bng khng c xt n (N.mm) (6.10.4.2-1) (6.10.4.3.1c)

Myc=sc khng mmen chy ca mt ct lin hp ca b phn c bc btng (N.mm) (6.12.2.3.1)

Myr=mmen khng khi chy khi s chy ca bn bng c tnh n (N.mm) (6.10.4.3.1c)

N=s chu k ca bin ng sut (6.6.1.2.5)

NDT=th nghim khng ph hoi

Ns=s cc mt phng ct; s cc mt phng trt mi bulng (6.13.2.7)(6.13.2.8)

n=s chu k cho mt lt xe ti qua; t s mun n hi ca thp i vi mun n hi ca btng; s lng cc neo chu ct trong mt ct ngang hoc s lng cc neo chu ct yu cu gia mt ct ca mmen dng ln nht v im k ca mmen 0,0 hoc gia tr v im k ca mmen 0,0; s lng cc sn tng cng dc; s lng bulng (6.6.1.2.5) (6.9.5.1) (6.10.3.1.1b) (6.10.7.4.1b) (6.11.2.3a)

nAc=s lng cc neo b xung thm yu cu trong cc vng ca cc im un tnh ti i vi cc mt ct khng lin hp trong cc vng un m (6.10.7.4.3)

Ph=lc trong bn cnh chu nn im c ging c gi tr mmen cao hn do ti trng tnh ton (N) (6.10.4.2.5a)

Pl=lc trong bn cnh chu nn im c ging c gi tr mmen thp hn do ti trng tnh ton (N) (6.10.4.2.5a)

Pn=sc khng danh nh, sc khng p mt danh nh, sc khng nn danh nh (N) (6.8.7.2) (6.9.2.1)

Pnu=sc khng ko danh nh i vi s t gy trong mt ct thc (N) (6.8.2.1)

Pny=sc khng ko danh nh i vi s chy do trong mt ct th (N)(6.8.2.1)

Pr=sc khng ko hoc nn dc trc tnh ton; sc khng p mt tnh ton trn cc bn c inh; sc khng ko danh nh ca mt cu, c xt chiu rng hiu dng ca mt cu (N)(6.8.2.1) (6.8.2.3) (6.8.7.2) (6.9.2) (6.14.3.3.2)

Pt=lc ko bulng ti thiu yu cu (N) (6.13.2.8)

Pu=lc dc trc tnh ton tc dng; lc ko trc tip hoc lc ct mi bulng do ti trng tnh ton; lc trong sn trc hng (N) (6.9.2.2) (6.13.2.10.4) (6.8.2.3) (6.13.2.11) (6.14.3.3.2)

p=khong cch u ca cc neo chu ct dc theo trc dc (mm) (6.10.7.4.1b)

Q=mmen th nht ca din tch bn tnh i ngn hn i vi trc trung ho c mt ct lin hp ngn hn trong cc vng un dng, hoc mmen th nht ca din tch ct thp dc i vi trc trung ho ca mt ct lin hp trong cc vng un m (mm3) (6.10.7.4.1b)

Qfl=t s ca kh nng chng on ca bn cnh vi cng chy ca bn cnh (6.10.4.2- 3)

Qn=cng ct danh nh ca mt neo chu ct (N) (6.10.7.4.4)

Qp= mnh ca bn cnh v bn bng chu nn t ti sc khng un M (6.10.4.2.3)

Qr=cc sc khng tnh ton ca cc neo chu ct (N) (6.10.7.4.4)

Qu=lc ko nh u ca mi bulng do ti trng tnh ton (N) (6.13.2.10.4)

R=s xoay do (MRADS); h s tng tc vi ct (6.10.10.2.4d) (6.10.7.3.3a)

Rb.Rh=cc h s gim ng sut bn cnh (6.10.4.3)

Rn=sc khng danh nh ca bulng lin kt hoc vt liu c lin kt (N) hoc (MPa) ( 6.13.2.2) (6.13.2.9)

(RPB)r=sc khng p ca mt cht (N) (6.7.6.2.2)

Rr=sc khng tnh ton ca lin kt bulng hoc hn trng thi gii hn cng (N) hoc (MPa) (6.13.2.2) (6.13.3.2)

Rs=sc khng ct danh nh ca bulng trong ct v ko kt hp (N) (6.13.2.11)

r=bn knh hi chuyn nh nht , bn knh hi chuynca np tng cng dc i vi mp tip xc bung (mm) (6.10.8.3.3) (GSA)

rs=bn knh hi chuyn ca thp hnh kt cu, ng hoc h ng i vi mt phng un dc (mm) (6.9.4.1) ( 6.9.5.1)

rt=i vi mt ct lin hp bn knh hi chuyn ca mt ct tnh i gm bn cnh chu nn ca mt ct thp cng vi mt phn ba chiu cao ca bn bng chu nn, i vi trc thng ng. i vi mt ct khng lin hp bn knh hi chuyn ca bn cnh chu nn i vi trc thng ng (mm) (6.10.4.2.5a) (6.10.4.1.9)

ry=bn knh hi chuyn nh nht ca mt ct thp i vi trc thng ng trong mt phng ca bn bng gia cc im ging (mm) (6.10.4.1.7)

S=mun mt ct n hi ca mt ct (mm3) (6.12.2.2.2)

SXC=mdun mt ct cu bn cnh chu nn i vi trc chnh nm ngang ca mt ct (mm3) (6.10.4.2.6a)

s=bc ca cc l; khong cch dc ca ct thp ngang (mm) (6.8.3) (6.12.3.1)

T=mmem xon trong do cc ti trng tnh ton (N.mm) (6.11.2.1.2a)

Tn=sc khng ko danh nh ca bulng (N) (6.12.2.10.2) (6.13.2.11)

Tu=lc ko mi bulng do t hp ti trng s dng (N) (6.13.2.11)

t=chiu dy bn (mm); chiu dy ng (mm) ; chiu dy ca bn bn ngoi mng hn hoc thp hnh (mm) (6.7.6.2.2) (6.9.4.2) (6.13.2.6.2)

tb=chiu dy bn cnh chu nn; chiu dy ca bn cnh truyn lc tp trung (mm) (6.10.7.4.4b) ( 6.13.7.2)

tc=chiu dy ca bn cnh ca cu kin cn c tng cng (mm) (6.13.7.2)

tf=chiu dy bn cnh chu nn (mm); Chiu dy bn cnh ca neo chu ct U (mm) (6.10.4.1.3) (6.10.7.4.4c)

tfb=chiu dy bn cnh di (mm) (6.10.3.5.1)

th=chiu dy ca nch bn btng trn bn cnh trn ca dm thp (mm) (6.10.A22b)

tp=chiu dy ca bn t ti phng ngang; Chiu dy ca phn nh ra ca sn tng cng; Chiu dy ca sn tng cng (mm) (6.6.1.2.5) (6.10.6.1.2) (6.11.3.2.1)

ts=chiu dy ca bn btng; Chiu dy ca bn sn tng cng (mm) (6.10.4.2.2b) ( 6.10.8.3.2)

tt=chiu dy ca bn cnh chu ko ca mt ct thp (mm) (6.10.7.4.4b)

tw=chiu dy bn bng ca neo chu ct hnh ( (mm); Chiu dy bn bng ca neo chu ct hnh U (mm) (6.12.3.2.1) (6.10.7.4.4c)

U=h s chit gim i vi tr trt, (yu trt) (6.8.2.1)

V=lc ct ph thm i vi cc bn khoan l (N) (6.9.4.3.2)

Vh=tng lc ct nm ngang do cc neo chng chu ct (N) (6.10.7.4.4b)

Vn=sc khng ct danh nh (N) (6.10.7.1)

Vp=kh nng chu ct do (N) (6.10.7.2)

Vr=sc khng ct tnh ton (N) (6.10.7.1)

Vsr=bin lc ct (N) (6.10.7.4.1b)

Vu=lc ct do ti trng tnh ton (N) (6.7.6.2.1)(6.10.8.1.4)

Vui=lc ct do cc ti trng tnh ton trn mt bung nghing (N) (6.11.2.2.1)

Vcf=ng sut ct do hot ti (N); lc ct trong bn bng ca mt ct ng nht vi cc np tng cng ngang v c hoc khng c cc np tng cng dc (N) (6.10.4.4)

W=chiu rng ca bn cnh gia cc np tng cng dc hoc khong cch t bn bn bng n np tng cng dc gn nht (mm) ; khong cch tim n tim gia cc bn cnh ca mt ct hp (mm) (6.11.3.2.1) (6.11.1.1.1)

Z=mun do ca mt ct (mm3) (6.12.2.3.1)

Zr=cng mi chng ct ca neo chu ct (N) (6.10.7.4.3)

Y=h s ti trng quy nh trong Bng 3.4.1.1 (6.6.1.2.2)

((f)=tc ng lc, bin ng sut hot ti do s i qua ca ti trng mi (MPa) (6.6.1.2.2)

((f)cn=sc chu mi danh nh i vi chi tit loi C (Mpa) (6.6.1.2.5)

((f)n=sc chu mi danh nh (MPa) (6.6.1.2.2) (6.6.1.2.5)

((FTH)=ngng mi bin khng i (MPa) (6.6.1.2.5)

(=h s mnh ca ct tiu chun ho (6.9.5.1) (6.9.4.1)

(b=h s lin quan n t s b/t (6.10.4.3.2)

(=gc nghing ca bn bng i vi mt phng thng ng () (6.11.2.2.1)

(b=h s sc khng i vi p mt (6.5.4.2)

(bb=h s sc khng i vi cc bulng p mt trn vt liu (6.5.4.2)

(bc=h s sc khng i vi ct khi (6.5.4.2)

(c=h s sc khng i vi nn (6.5.4.2)

(e1=h s sc khng i vi ct trong kim loi hn trong cc ng hn ngu hon ton trc giao vi trc ca ng hn ngu khng hon ton (6.5.4.2)

(e2=h s sc khng i vi kim loi hn ca cc ng hn ngu khng hon ton (6.5.4.2)

(f=h s sc khng i vi un (6.5.4.2)

(s=h s sc khng i vi ct trong cc bulng (6.5.4.2)

(sc=h s sc khng i vi cc neo chu ct (6.5.4.2)

(t=h s sc khng i vi ko trong cc bulng cng cao (6.5.4.2)

(u=h s sc khng i vi t gy ca cc cu kin chu ko (6.5.4.2)

(v=h s sc khng i vi ct (6.5.4.2)

(w=h s sc khng i vi ct trong cc ng hn (6.5.4.2)

(y=h s sc khng i vi chy ca cc cu kin chu ko (6.5.4.2)

6.4. vt liu

6.4.1. Cc loi thp kt cu

Cc loi thp kt cu phi tun theo cc yu cu, quy nh trong Bng 1 v thit k phi cn c trn cc tnh cht ti thiu c nu.

Mun n hi v h s gin n nhit ca tt c cc cp ca thp kt cu phi gi nh l 200.000 MPa v 11,7x10-6 mm/mm/ oC.

Thp theo AASHTO M270M, cp 250, (ASTM A709M, cp 250) c th c s dng vi cc chiu dy trn 100 mm cho cc ng dng khng phi l kt cu hoc cc b phn ca h gi ta.

Cc thp hnh kt cu hp kim ti v ram v ng ng khng hn vi cng ko ti a quy nh khng vt qu 965 MPa i vi cc thp hnh kt cu, hoc 1000 MPa i vi ng ng khng hn, c th c s dng, min l:

Vt liu p ng tt c cc yu cu c - ha khc ca ASTM A709M, cp 690 hoc 690 W, v

Thit k c cn c trn cc c tnh ti thiu quy nh i vi thp ASTM A709M, cc cp 690 v 690 W

ng ng kt cu phi c hn to hnh ngui hoc ng khng hn tun theo ASTM A500, cp B, hoc hn to hnh nng hoc ng khng hn tun theo ASTM A501.

Cc gii hn chiu dy lin quan n cc thp hnh cn v cc nhm phi tun theo ASTM A6M (AASHTO M160).

Bng 6.4.1.1 - Cc c tnh c hc ti thiu ca thp kt cu theo hnh dng, cng v chiu dy

K hiu AASHTOThp kt cuThp hp kim thp cng caoThp hp kim thp ti v ramThp hp kim ti & ram, cng chy do cao

M270M

Cp 250M270M

Cp 345M270M

Cp 345WM270M

Cp 485WM270M

Cc cp 690/690 W

K hiu ASTM tng ngA 709M

Cp 250A 709M Cp 345A 709M Cp 345WA 709M Cp 485WA 709M Cc cp 690/690 W

Chiu dy ca cc bn, mmTi 100Ti 100Ti 100Ti 100Ti 65Trn 65 n 100

Thp hnhTt c cc nhmTt c cc nhmTt c cc nhmKhng p dngKhng p dngKhng p dng

Cng chu ko nh nht, Fu, MPa400450485620760690

im chy nh nht hoc cng chy nh nht Fy, MPa250345345485690620

6.4.2. Cht, con ln v con lc

Thp cho cc cht, con ln v con lc phi tun theo cc yu cu ca Bng 1, Bng 6.4.1.1 hoc iu 6.4.7.

Cc con ln phi c ng knh khng nh hn 100 mm.

Bng 6.4.2-1 - Cc c tnh c hc ti thiu ca cc cht, cc con ln v cc con lc theo kch thc v cng

K hiu AASHTO vi cc gii hn kch thcM169 ng knh 100mm hoc nh hnM102 n ng knh 500 mmM102 n ng knh 500 mmM102 n ng knh 250 mmM102 n ng knh 500 mm

K hiu ASTM, cp hoc hngA108

Cc cp 1016 n 1030A668

Hng CA668

Hng DA668

Hng FA668

Hng G

im chy nh nht Fy, MPa250230260345345

6.4.3. Bulng, ai c v vng m

6.4.3.1. Bulng

Cc bulng phi tun theo mt trong cc tiu chun sau y:

Tiu chun k thut i vi cc bulng v inh tn thp cacbon, cng chu ko 420 MPa, ASTM A307

Tiu chun k thut i vi cc bulng cng cao cho cc lin kt thp kt cu vi cng ko ti thiu 830MPa i vi cc ng knh t 16mm ti 27mm v 725MPa i vi cc ng knh t 30mm ti 36mm, AASHTO M164M (ASTM A325M), hoc

Tiu chun k thut i vi cc bulng cng cao, cc hng 10.9 v 10.9.3 cho cc lin kt thp kt cu, AASHTO M253M (ASTM A490M).

Cc bulng loi 1 nn s dng vi cc thp khc vi thp c s l chng n mn. Cc bulng loi 3 tun theo ASTM A325M hoc ASTM A490M phi c s dng vi cc thp c s l chng n mn. AASHTO M164 (ASTM A325M), loi 1, cc bulng c th hoc trng km nhng nng ph hp vi AASHTO M232 (ASTM A153), Hng C, hoc trng km bng c hc ph hp AASHTO M298 (ASTM B695), Hng 345 (50). Cc bulng trng km phi c th nghim ko sau khi trng km, nh AASHTO M164 (ASTM A325M) yu cu.

Cc bulng AASHTO M253M (ASTM A490M) khng c trng km.

Cc vng m, ai c v bulng ca bt c lin kt no phi c trng km theo cng phng php. Cc ai c cn c ph ln nhau ti s lng ti thiu yu cu i vi lp ghp linh kin lin kt, v phi c bi trn bng du nhn c mu sc trng thy c.

6.4.3.2. ai cTr ch thch di, cc ai c cho cc bulng AASHTO M164M (ASTM A325M) phi tun theo tiu chun k thut i vi cc ai c thp ccbon v hp kim, AASHTO M291M (ASTM A563M), cc cp 12, 10S3, 8S, 8S3, 10 v 10S hoc tiu chun k thut i vi cc ai c thp ccbon v hp kim cho cc bulng lm vic di p sut cao v nhit cao, AASHTO M292M (ASTM A194M), cc cp 2 v 2H.

Cc ai c cho bulng ca AASHTO M253M (ASTM A490M) phi tun theo cc yu cu ca AASHTO M291M (ASTM A563M) cc cp 12 v 10S3 hoc AASHTO M292M (ASTM A194M) cp 2H.

Cc ai c trng km phi c x l nhit, cp 2H, 12 hoc 10S3. Cc quy nh ca iu 6.4.3.1 phi c p dng.

Cc ai c phi c cng ti thiu l 89HRB.

Cc ai c s dng theo AASHTO M164M (ASTM A325M), cc bulng loi 3 phi l cp C3 hoc DH3. Cc ai c s dng theo AASHTO M253M (ASTM A490M), cc bulng loi 3 phi l cp DH3.6.4.3.3. Vng mCc vng m phi tun theo tiu chun k thut i vi cc vng m thp ti, ASTM F43 GM).

Cc quy nh ca iu 6.4.3.1 phi c p dng cho cc vng m trng km.

6.4.3.4. Cc linh kin lin kt ty chnCc linh kin lin kt khc hoc cc cm linh kin lin kt cho n nay khng c quy nh c th c s dng ty theo s chp thun ca k s, min l chng p ng cc im sau y:

Cc vt liu, cc yu cu sn xut v thnh phn ha hc ca AASHTO M164M (ASTM A325M) hoc AASHTO M253M (ASTM A490M),

Cc yu cu c tnh c hc ca cng quy trnh trong cc th nghim theo kch thc thc, v

ng knh thn v cc khu vc p ta di u v ai c, hoc b phn tng ng ca chng, khng c nh hn cc thng s quy nh cho mt bulng v ai c c cng cc kch thc danh nh c m t trong cc iu 6.4.3.1 v 6.4.3.2.

Cc linh kin lin kt la chn nh th c th khng ging cc kch thc khc ca bulng, ai c v vng m quy nh trong cc iu 6.4.3.1 n 6.4.3.3.

6.4.3.5. Thit b ch bo ti trngCc thit b ch bo ti trng tun theo cc yu cu ca Tiu chun k thut i vi cc ch bo lc cng trc tip loi vng m c th p c s dng vi cc linh kin lin kt kt cu, ASTM F959M, c th c s dng cng vi cc bulng, ai c v vng m.

Cc thit b ch bo lc cng trc tip khc c th c s dng ty theo s chp thun ca k s.

6.4.4. inh neo chu ct

Cc inh neo chu ct phi c lm t cc thanh thp ko ngui, cc cp 1015, 1018 hoc 1020, kh mt phn hoc kh hon ton xy, tun theo AASHTO M169 (ASTM A108) - Tiu chun k thut i vi cc thanh thp ccbon gia cng ngui, cht lng tiu chun, v phi c gii hn chy nh nht l 345 MPa v cng chu ko l 400MPa. Nu s nng chy dng gi cc m inh th thp dng cho cc m phi l cp ccbon thp ph hp vi hn v phi tun theo ASTM A109M - Tiu chun k thut i vi thp, ccbon, thp l cn ngui.

6.4.5. Kim loi hn

Kim loi hn phi tun theo cc yu cu ca Quy phm Hn cu D1.5 ANSI/AASHTO/AWS.

6.4.6. Kim loi c

6.4.6.1. Thp c v gang doThp c phi tun theo mt trong cc tiu chun sau y:

AASHTO M192M - Tiu chun k thut i vi vic c thp cho cu ng b, Hng 485, tr khi c quy nh khc.

AASHTO M103M (ASTM A27M) - Tiu chun k thut i vi vic c thp ccbon cho ng dng chung, Cp 485-250, tr khi c quy nh khc.

AASHTO M163M (ASTM A743M) - Tiu chun k thut i vi vic c hp kim da vo gang pha crom chng n mn, gang pha crom-niken cho ng dng chung, cp CA15, tr khi c quy nh khc.

Sn phm c bng gang do phi tun theo Tiu chun k thut i vi gang do c, ASTM A536, cp 414-276-18, tr khi c quy nh khc.

6.4.6.2. Cc sn phm c c th rn cCc sn phm c c th rn c phi tun theo ASTM A47M, Cp 24118, - Quy trnh i vi cc sn phm gang ferit c th rn c. Cng chy do nh nht phi khng thp hn 241MPa.

6.4.6.3. Gang

Cc sn phm gang phi tun theo AASHTO M105 (ASTM A48M), Hng 30 - Quy trnh i vi cc sn phm c hp kim xm.

6.4.7. Thp khng g

Thp khng g phi tun theo mt trong cc tiu chun sau y:

ASTM A176- Tiu chun k thut i vi thp tm, thp l v thp di khng g v thp pha crm chu nhit

ASTM A240M- Tiu chun k thut i vi thp tm, thp l v thp di pha crm chu nhit v thp khng g, cho cc bnh chu p sut

ASTM A276- Tiu chun k thut i vi thp thanh v thp hnh chu nhit v khng g, hoc

ASTM A666- Tiu chun k thut i vi thp l, thp di, thp tm, thanh dt austenit khng g cho cc p dng kt cu.

Thp khng g khng tun theo cc Tiu chun lit k trn y c th c s dng min l thp tun theo cc yu cu c-ha hc ca mt trong cc Tiu chun lit k trn y, hoc cc Tiu chun khc ban hnh. Cc Tiu chun ny quy nh cc tnh cht v s thch hp, min l thp phi qua cc phn tch, th nghim v cc kim tra khc cng mc v theo cch m t ca mt trong cc Tiu chun lit k.

6.4.8. Dy thp

6.4.8.1. Dy thp trnDy thp trn phi tun theo ASTM A510M - Tiu chun k thut i vi cc yu cu chung cho cc phi cn ko dy v dy trn th, thp ccbon.

6.4.8.2. Dy thp trng kmDy thp trng km phi tun theo ASTM A641M - Tiu chun k thut i vi dy thp ccbon bc km (trng km).

6.4.8.3. Dy thp bc poxyDy thp bc poxy phi tun theo ASTM A99 - Tiu chun k thut i vi dy thp bc poxy.

6.4.8.4. Dy cp cuDy cp cu phi tun theo ASTM A586 - Tiu chun k thut i vi dy cp kt cu si thp bc km song song v xon, hoc ASTM A603 - Tiu chun i vi cp thp kt cu bc km.

6.5. cc trng thi gii hn

6.5.1. Tng qut

c tnh kt cu ca cc b phn c lm t thp hoc thp phi hp vi cc vt liu khc, phi c iu tra cho tng giai on c th tr nn nguy kch trong khi thi cng, bc xp, vn chuyn v lp rp, cng nh trong tui th phc v ca kt cu m chng l mt phn.

Cc b phn kt cu phi cn xng tha mn cc yu cu v cc trng thi gii hn cng , c bit, s dng v mi.

6.5.2. Trng thi gii hn s dng

Phi p dng cc quy nh ca cc iu 2.5.2.6 v 6.10.5 khi c th p dng c.

Cc kt cu thp phi tha mn cc yu cu i vi t hp ti trng s dng trong Bng 3.4.1-1 lu Ghi ch 6.

6.5.3. Trng thi gii hn mi v ph hoi

Cc b phn cu thnh v cc chi tit phi c iu tra v mi nh quy nh trong iu 6.10.6

Phi p dng t hp ti trng mi, quy nh trong Bng 3.4.1-1 v hot ti mi quy nh trong iu 3.6.1.4.

Cc bn bng ca dm bn phi tha mn cc quy nh ca iu 6.10.6.

Phi p dng cc iu khon i vi mi trong cc neo chu ct trong cc iu 6.10.7.4.2 v 6.10.7.4.3 khi c th p dng c.

Cc bulng chu mi do ko phi tha mn cc quy nh ca iu 6.13.2.10.3.

Cc yu cu bn chng t gy phi ph hp vi iu 6.6.2.

6.5.4. Trng thi gii hn cng

6.5.4.1. Tng qutCng v n nh phi c xem xt bng s dng cc t hp ti trng cng quy nh trong Bng 3.4.1-1.

6.5.4.2. H s sc khngCc h s sc khng, , i vi trng thi gii hn cng phi ly nh sau:

i vi un(f = 1,00

i vi ct(v = 1,00

i vi nn dc trc, ch cho thp(c = 0,90

i vi nn dc trc, lin hp(c = 0,90

i vi ko, t trong mt ct thc(u = 0,80

i vi ko, chy trong mt ct nguyn(y = 0,95

i vi p mt ta trn cc cht, cc l doa, khoan hoc bt bulng v cc b mt cn(b = 1,00

i vi cc bulng p mt trn vt liu...... (bb = 0,80

i vi cc neo chu ct(sc = 0,85

i vi cc bulng A325M v A490M chu ko(t = 0,80

i vi cc bulng A307 chu ko(t = 0,80

i vi cc bulng chu ct(s = 0,65

i vi cc bulng A325M v A490M chu ct(s = 0,80

i vi ct khi(bs= 0,80

i vi kim loi hn trong cc ng hn ngu hon ton:

+ ct trn din tch hu hiu(e1= 0,85

+ ko hoc nn trc giao vi din tch hu hiu( = ( kim loi nn

+ ko hoc nn song song vi trc ca ng hn( = ( kim loi nn

i vi kim loi hn trong cc ng hn ngu cc b:

+ ct song song vi trc ca ng hn(e2 = 0,80

+ ko hoc nn song song vi trc ca ng hn( = ( kim loi nn

+ nn trc giao vi din tch hu hiu( = ( kim loi nn

+ ko trc giao vi din tch hu hiu (e1= 0,80

i vi kim loi hn trong cc mi hn:

+ ko hoc nn song song vi trc ca ng hn(= (kim loi nn

+ ct trong chiu cao tnh ton ca kim loi hn(e2 = 0,80

i vi sc khng trong khi ng cc(e1 = 1,00

6.5.5. Trng thi gii hn c bit

Phi nghin cu tt c cc t hp ti trng c bit c th p dng ghi trong Bng 3.4.1-1.

Tt c cc h s sc khng i vi trng thi gii hn c bit, tr i vi cc bulng, u phi ly bng 1,0

Cc mi lin kt bng bulng khng c bo v bng thit k theo kh nng hoc theo trng thi chy kt cu c th c gi nh lm vic nh cc lin kt loi ma st trng thi gii hn c bit v phi dng cc gi tr ca cc h s sc khng i vi cc bulng ni trong iu 6.5.4.2.

6.6. cc xem xt v mi v t gy

6.6.1. Mi

6.6.1.1. Tng qut mi phi c phn loi hoc do ti trng gy ra hoc do cong vnh gy ra mi.

6.6.1.2. Mi do Ti trng gy ra 6.6.1.2.1. p dng

Tc dng lc xem xt thit k mi ca chi tit cu thp phi l bin ng sut ca hot ti.

Cc ng sut d khng c xt n trong nghin cu mi.

Cc quy nh ny ch p dng cho cc chi tit chu ng sut ko thc. Trong cc vng m cc ti trng thng xuyn khng c nhn vi h s, gy ra lc nn, th mi ch c xt nu nh ng sut nn ny nh hn hai ln ng sut hot ti ko ln nht gy ra t t hp ti trng mi quy nh trong Bng 3.4.1-1.

6.6.1.2.2. Cc tiu ch thit k

i vi cc nghin cu mi do ti trng gy ra, mi chi tit phi tha mn:

Y((f) ( ((F)n (6.6.1.2.2-1)

trong :

Y = h s ti trng quy nh trong Bng 3.4.1-1 i vi t hp ti trng mi

((f) = tc dng lc, phm vi ng sut hot ti do s i qua ca ti trng mi nh quy nh trong iu 3.6.1.4 (MPa)

((F)n= sc chu mi danh nh nh quy nh trong iu 6.6.1.2.5 (MPa)

6.6.1.2.3. Phn loi cc chi tit

Cc b phn v cc chi tit vi sc chu mi nh hn hoc bng chi tit loi C phi c thit k tha mn cc yu cu ca cc loi chi tit tng ng; nh tm tt trong cc Bng 1 v 2, v c cho trong Hnh 1.

Bng 6.6.1.2.3-1 - Cc loi chi tit i vi ti trng gy ra mi

iu kin chungTrng thiLoi chi titTh d minh ha, xem hnh 6.6.1.2.3-1

Cc cu kin thngKim loi c bn:

Vi cc b mt cn v lm sch. Cc mp ct bng la vi ANSI/AASHTO/AWS D1.5 (Bn cnh 3.2.2), nhn 0,025mm hoc thp hn

Thp c x l chng n mn khng sn, tt c cc cp c thit k v cu to theo ng vi FHWA (1990)

mt ct thc ca cc u ca thanh c tai treo v cc bn cht.A

B

E1,2

Kt cu t hpKim loi c bn v kim loi hn trong cc b phn, khng c cc gn kt ph, c lin kt bng:

Cc ng hn rnh lin tc ngu hon ton vi cc thanh m lt ly i, hoc

Cc ng hn lin tc song song vi phng ca ng sut

Cc ng hn rnh lin tc ngu hon ton vi cc thanh m lt li, hoc

Cc ng hn rnh lin tc ngu khng hon ton song song vi phng ca ng sut

Kim loi c bn cc u ca cc bn ph trn mt phn chiu di:

Vi cc lin kt u bng bulng trt ti hn

Hp hn bn cnh, vi c hoc khng c cc mi hn u, hoc rng hn bn cnh vi cc mi hn u

+ Chiu dy bn cnh ( 20mm

+ Chiu dy bn cnh > 20mm

Rng hn bn cnh khng c cc mi hn u.B

B

BBB

E

EE3,4,5,7

22

7

iu kin chungTrng thiLoi chi titTh d minh ha, xem hnh 6.6.1.2.3.1

Cc lin kt ni i u ng hn rnh c lnh ln mi hn c kim sot bng th nghim khng ph hoi NDT v tt c c mi theo phng ca cc ng sutKim loi c bn v kim loi hn cc mi ni i u hn rnh ngu hon ton:

Ca cc bn c mt ct ngang tng t vi cc mi hn c lm phng n bn thp nn

Vi cc chuyn tip bn knh 600mm v chiu rng vi cc mi hn c lm phng n bn nn

Vi cc chuyn tip v chiu rng hoc chiu dy vi cc mi hn phng n bn nn to cc dc khng dc hn 1,0 n 2,5

+ Cc cp kim loi c bn 690/690W

+ Cc cp kim loi c bn khc

Vi c hoc khng c cc chuyn tip c cc dc khng ln hn 1,0 n 2,5, khi ct thp hn khng c ly iB

B

BB

C

8,10

13

11,12

8,10,11,12

Cc chi tit gn kt ph hn bng hn rnh, t ti theo chiu dcKim loi c bn cc chi tit c lin kt bng cc ng hn rnh ngu hon ton hay khng hon ton:

Khi chiu di chi tit theo phng ca ng sut tc dng:

+ Nh hn 50 mm

+ Gia 50 mm v 12 ln chiu dy ca chi tit, nhng nh hn 100 mm

+ Ln hn hoc 12 ln chiu dy ca chi tit, hoc 100 mm

- chiu dy chi tit < 25 mm

- chiu dy chi tit ( 25 mm

Vi bn knh chuyn tip vi cc mi hn u nhn n nn, khng k ti chiu di ca chi tit:

+ Bn knh chuyn tip ( 600 mm

+ 600 mm>bn knh chuyn tip (150 mm

+ 150mm>bn knh chuyn tip ( 50 mm

+ Bn knh chuyn tip < 50 mm

Vi bn knh chuyn tip vi cc mi hn u khng nhn n bn nnC

D

E

E'

B

C

D

E

E6,15

15

15

15

16

16

iu kin chungTrng thiChi titTh d minh ha, xem hnh 6.6.1.2.3.1

Cc chi tit gn kt ph hn bng ng hn rnh, t ti theo chiu ngang c tnh lnh ln mi hn c kim sot bng NDT v tt c c mi ngang theo hng ng sutKim loi c bn cc chi tit c lin kt bng cc ng hn rnh ngu hon ton vi bn knh chuyn tip:

Vi chiu dy bn bng nhau v ct hn ly i:

+ Bn knh chuyn tip ( 600 mm

+ 600 mm> bn knh chuyn tip ( 150 mm

+ 150 mm> bn knh chuyn tip ( 50 mm

+ Bn knh chuyn tip < 50 mm

Vi chiu dy bn bng nhau v ct hn khng ly i:

+ bn knh chuyn tip ( 150 mm

+ 150 mm > Bn knh chuyntip ( 50 mm

+ bn knh chuyn tip < 50 mm

Vi chiu dy bn bng nhau v ct hn khng ly i:

+ bn knh chuyn tip ( 50 mm

+ bn knh chuyntip < 50 mm

i vi mi bn knh chuyn tip vi chiu dy bn khng bng nhau v ct hn khng ly iB

C

D

E

C

D

E

D

E

E

16

Cc lin kt hn gc vi ng hn trc giao vi phng ca ng sutKim loi c bn:

cc chi tit khc vi cc lin kt ca g tng cng ngang cho bn cnh hoc ca g tng cng ngang cho bn bn bng

chn ca cc mi hn ca g tng cng ngang cho bn cnh v g tng cng ngang cho bn bn bngNh hn C hoc P/trnh 6.6.1.2.5-3

C'14

6

Cc lin kt hn gc vi ng hn trc giao v/hoc song song vi phng ca ng sutng sut ct trn chiu cao mi hnE9

iu kin chungTrng thiChi titTh d minh ha, xem hnh 6.6.1.2.3.1

Cc chi tit gn kt ph hn bng ng hn gc, t ti theo chiu dcKim loi c bn cc chi tit c lin kt bng cc ng hn gc:

Khi chiu di ca chi tit trong phng ca ng sut l:

+ nh hn 50 mm hoc cc neo chng ct loi inh neo

gia 50 mm v 12 ln chiu dy chi tit, nhng nh hn 100 mm

ln hn hoc 12 ln chiu dy chi tit hoc 100 mm

- chiu dy chi tit < 25mm

- chiu dy chi tit ( 25mm

Vi bn knh chuyn tip vi cc mi hn u nhn n bn nn, khng k ti chiu di ca chi tit.

+ bn knh chuyn tip ( 50mm

+ bn knh chuyn tip < 50mm

Vi bn knh chuyn tip vi cc mi hn u khng nhn n bn nn.C

D

E

E/

D

E

E15, 17, 18, 20

15,17

7,9,15,17

16

16

Cc chi tit gn kt ph hn bng ng hn gc, t ti theo chiu ngang, vi cc ng hn song song vi phng ca ng sut chnhKim loi c bn cc chi tit c lin kt bng cc ng hn gc:

Vi bn knh chuyn tip vi cc mi hn u nhn n bn mm:

bn knh chuyn tip ( 50 mm

bn knh chuyn tip < 50 mm

Vi mi bn knh chuyn tip vi cc mi hn u khng nhn n bn nnD

E

E16

Cc lin kt c gn cht bng c khKim loi c bn

mt ct nguyn ca cc lin kt ma st bng bulng cng cao, tr cc mi ni t ti trng theo trc trong s un ngoi mt phng c gy ra trong cc vt liu lin kt

mt ct thc ca cc lin kt khng ma st c bulng cng cao

mt ct thc ca cc lin kt tn inh

B

B

D21

iu kin chungTrng thiLoi chi titTh d minh ha, xem hnh 6.6.1.2.3-1

Thanh c tai treo hoc cc bn chtKim loi c bn mt ct thc ca u thanh c tai treo hoc bn cht

Kim loi c bn trong thn thanh c tai treo, hoc thng qua mt ct th ca bn cht vi:

Cc mt cn hoc nhn

Cc cnh ct bng laE

A

B23,24

23,24

23,24

Hnh 6.6.1.2.3-1 - Cc th d minh ho

Bng 6.6.1.2.3-2 - Cc loi chi tit i vi ti trng gy ra mi ca cc mt cu trc hng

Bng 6.6.1.2.3-2 (tip theo)

6.6.1.2.4. Cc chi tit s dng hn ch

Khng c s dng cc ng hn rnh ngu khng hon ton chu ti trng theo chiu ngang th khng c php s dng tr khi c cho php iu 9.8.3.7.2.

Khng c s dng cc bn lin kt vo cc b mt bn cnh dm ch bng cc ng hn gc ngang.

6.6.1.2.5. Sc khng mi

Tr trng hp quy nh di y, sc khng mi danh nh phi c ly nh sau:

((F)n = ( ((F)TH (6.6.1.2.5-1)

vi:

N = (365) (100) n (ADTT)SL (6.6.1.2.5-2)

trong :

A = hng s ly t Bng 1 (MPa3)

n = s cc chu k phm vi ng sut i vi mi lt chy qua ca xe ti, ly t Bng2

(ADTT)SL = ADTT mt ln xe chy nh quy nh trong iu 3.6.1.4

((F)TH = ngng mi bin khng i, ly t Bng 3 (MPa)

Phm vi sc khng mi danh nh i vi kim loi c bn cc chi tit lin kt bng cc ng hn gc chu ti trng ngang, ni m bn khng lin tc b chu ti, phi c ly nh hn ((F)cn v:

((F)n =

(6.6.1.2.5-3)

trong :

= sc khng mi danh nh i vi chi tit loi C (MPa)

H = chiu cao hiu dng ca ng hn gc (mm)

tp = chiu dy ca bn chu ti (mm).

Bng 6.6.1.2.5-1 - Hng s loi chi tit, A

Loi chi titHng s A nhn 1011 (MPa3)

A82,0

B39,3

B'20,0

C14,4

C'14,4

D7,21

E3,61

E'1,28

Bulng M164 M (A325M) chu ko dc trc5,61

Bulng M253 M (A490M) chu ko dc trc10,3

Bng 6.6.1.2.5-2 - Cc chu k i vi mi lt xe ti chy qua, n

Cc cu kinChiu di nhp

dc> 12000 mm( 12000 mm

Cc dm nhp gin n1,02,0

Cc dm lin tc

1) Gn gi ta pha trong1,52,0

2) ni khc1,02,0

Cc dm hng5,0

Cc gin1,0

Khong cch

Cc cu kin ngang> 6000 mm( 6000 mm

1,02,0

Bng 6.6.1.2.5-3 - Gii hn mi - bin khng i

Loi chi titGii hn (MPa)

A165

B110

B'82,7

C69,0

C'82,7

D48,3

E31,0

E'17,9

Bulng M164M (A325M) chu ko dc trc214

Bulng M253M (A490M) chu ko dc trc262

6.6.1.3. Mi do xon vn gy ra (hoc vn mo)

Cc ng truyn ti phi m bo truyn tt c cc lc d kin v khng c d kin phi c b tr bng cch lin kt tt c cc b phn ngang vo cc thnh phn thch hp. Cc thnh phn ny bao gm cc mt ct ngang ca b phn dc. Cc ng truyn ti phi c b tr bng cch lin kt cc thnh phn khc nhau thng qua hn ni hoc bt bulng.

kim tra s on v un n hi ca bn bng, phi tha mn quy nh ca iu 6.10.6.

6.6.1.3.1. Cc bn lin kt ngang

Cc bn lin kt phi c hn hoc bt bulng vo c cc bn cnh chu nn v chu ko ca mt ct ngang m :

Cc vch ngn hoc cc khung ngang lin kt c gn ni vo cc bn lin kt ngang, hoc cc g tng cng ngang thc hin chc nng nh cc bn lin kt

Cc vch ngn trong hoc ngoi hoc cc khung ngang c gn ni vo cc bn lin kt ngang, hoc cc g tng cng ngang thc hin chc nng nh cc bn lin kt, v

Cc dm sn c gn ni vo cc bn lin kt ngang, hoc cc g tng cng ngang thc hin chc nng nh cc bn ni.

Khi khng c nhiu thng tin hn cn thit k lin kt bng hn hoc bng bulng chu c ti trng nm ngang 90.000N i vi cc cu thng, khng cho.

6.6.1.3.2. Bn lin kt ngang

Gn ni cc bn lin kt nm ngang vo cc bn cnh l khng thc t, vy cc bn lin kt nm ngang trn cc bn bng c g tng cng cn c t mt khong cch thng ng khng nh hn mt na chiu rng ca bn cnh trn hoc di bn cnh. Cc bn lin kt nm ngang gn ni vo cc bn bng khng c g tng cng cn c t t nht l 150 mm trn hoc di bn cnh, nhng khng nh hn mt na chiu rng ca bn cnh nh quy nh trn.

Cc u ca cc b phn lin kt nm ngang trn bn lin kt nm ngang phi c gi khong cch ti thiu l 100 mm k t bn bng v bt k g tng cng ngang no.

nhng ni c g tng cng, th cc bn lin kt nm ngang phi c nh tm trn g tng cng, d bn ny c cng pha vi g tng cng trn bn bng hay khng. ch no bn lin kt nm ngang cng pha vi g tng cng, th bn phi c gn ni vo g tng cng. Thanh tng cng ngang v tr no phi c lin tc t bn cnh chu nn n bn cnh chu ko v phi c gn ni vo c hai bn cnh.

6.6.1.3.3. Mt cu trc hng

Lp bn v chi tit phi tha mn tt c cc yu cu ca iu 9.8.3.7

6.6.2. Ph hoi

Tt c cc b phn chnh v cc lin kt chu cc tc dng lc ko do t hp ti trng theo cng I, nh quy nh trong Bng 3.4.1-1, v cc b phn khc yu cu dai chng t gy ca rnh ch V Charpy, phi c ch nh r trn cc bn v hp ng.

Vng nhit thch hp phi c xc nh t nhit nh nht c th s dng c, nh quy nh trong Bng 1, v phi c ch nh r trong cc ti liu hp ng.

Cc yu cu bn chng t gy phi theo ng vi Bng 2 i vi vng nhit thch hp. Cng chy phi ly theo gi tr ghi trong Bo co th nghim ca Nh my chng nhn.

Nu cng chy ca M270M AASHTO, cc cp 345/345W (ASTM A709M, cp 345/345W) vt qu 450MPa th nhit th phi gim i 8oC i vi mi lng gia tng 70MPa trn 450 MPa. Nu cng chy ca M270M AASHTO, cp 485/485W (ASTM A709M, cp 485W) vt qu 585 MPa, th nhit th phi gim i 8oC i vi mi lng gia tng 70 MPa trn 585 MPa.

M270M AASHTO, cc cp 690/690W (ASTM A709W, cc cp 690/690W) phi p ng cc yu cu ca Vng 2 xem nh l ti thiu.

K s phi c trch nhim xc nh, nu c, b phn no l b phn nguy kch v t gy FCM. V tr ca tt c cc FCM phi c m t r rng trn cc bn v hp ng. Vt liu cho cc b phn nguy kch v t gy hoc cc thnh phn c ch nh l FCM, phi c th nghim ph hp vi T243M AASHTO (ASTM A673M), tn s P. Ch ring i vi Vng 3, cc th nghim phi c thc hin trn mi u ca mi bn thp cn.

Vt liu cho cc b phn khng c ch nh l nguy kch v t gy phi c th nghim ph hp vi T243M AASHTO (ASTM A673), tn s H.

Mi chi tit ph c chiu di theo phng ca ng sut ko ln hn 100 mm m c hn vo khu vc chu ko ca mt b phn thuc FCM phi c xem l mt phn ca b phn chu ko v n phi c xem nh l nguy kch v t gy.

Bng 6.6.2-1 - Tn vng nhit i vi cc yu cu ca rnh ch V Charpy

Nhit dng nh nhtVng nhit

-18oC v trn1

-19oC n -34oC2

-35oC n -51oC3

6.7. Cc yu cu v kch thc chung v chi tit

6.7.1. Chiu di hiu dng ca nhp

Cc chiu di nhp phi c ly bng khong cch gia cc tim ca cc gi hoc cc im khc ca tr ta.

6.7.2. vng tnh ti

Cc cu thp nn lm vng ngc trong khi ch to b li vng tnh ti v trc dc tuyn.

C th dng cch thay i chn la chiu di ca b phn, khi thch hp, trong cc h gin, vm v dy vng :

iu chnh vng tnh ti cho ph hp vi v tr hnh hc cui cng,

Gim hoc loi tr vic lm ngn sn, v

iu chnh biu mmen tnh ti trong cc cu siu tnh.

6.7.3. Chiu dy nh nht ca thp

Thp kt cu, bao gm ging lin kt, cc khung ngang v tt c cc loi bn tit im, loi tr i vi cc bn bng bng thp hnh cn, cc sn mt ct kn trong cc mt cu trc hng, cc con m v trong cc lan can tay vn, u phi lm bng thp c chiu dy khng nh hn 8 mm.

Chiu dy bn bn bng ca cc dm thp cn hoc thp hnh U v ca cc sn mt ct kn trong cc mt cu trc hng khng c nh hn 7,0 mm.

ni no kim loi d kin b ph ra chu cc nh hng n mn nghim trng, th phi c bo v c bit chng n mn, hoc chiu dy ca kim loi b hy sinh phi c quy nh.

6.7.4. Vch ngn v khung ngang

6.7.4.1. Tng qutCc vch ngn hoc cc khung ngang c th c t u ca kt cu nhp, qua cc gi ta bn trong, v cch qung dc theo nhp.

S cn thit v cc vch ngn hoc cc khung ngang phi c nghin cu cho tt c cc giai on ca cc phng php thi cng gi nh v iu kin cui cng. Vic nghin cu ny cn bao gm, nhng khng b gii hn cc ni dung sau y:

Truyn cc ti trng gi nm ngang t y dm ti mt cu v t mt cu xung ti cc gi,

S n nh ca bn cnh di i vi tt c cc ti trng khi l chu nn,

S n nh ca cc bn cnh trn trong chu nn trc khi x l mt cu, v

S phn b cc hot ti v tnh ti thng ng tc dng ln kt cu nhp cu.

Cc vch ngn hoc cc khung ngang yu cu v cc iu kin khc vi iu kin cui cng c th c nh r l phi dng ging lin kt tm.

Nu cc vch ngn hoc cc khung ngang c nh c bao gm trong m hnh kt cu s dng xc nh cc tc dng lc, th chng phi c thit k cho tt c cc trng thi gii hn c th p dng c i vi cc tc dng lc tnh ton. Cc vch ngn v cc khung ngang phi c thit k nh l iu kin ti thiu, truyn cc ti trng gi theo cc quy nh ca iu 4.6.2.7, v phi p ng tt c cc yu cu ca mnh c th p dng c trong hoc iu 6.8.4 hoc iu 6.9.3.

Cc bn lin kt i vi cc vch ngang v cc khung ngang phi tha mn cc yu cu quy nh trong iu 6.6.1.3.1.

u ca nhp cu v cc im trung gian l ni m s lin tc ca bn b gin on, cc mp ca bn phi c bi cc vch ngn hoc cc kt cu thch hp khc nh ch nh trong iu 9.4.4.

6.7.4.2. Dm thng c mt ct I Cc vch ngang hoc cc khung ngang cho cc dm thp cn phi cao t nht bng na chiu cao ca dm. Cc vch ngn hoc cc khung ngang cho cc dm bn phi cng cao cng tt.

Cc vch ngang hoc cc khung ngang u phi cn xng truyn tt c cc lc nm ngang ti cc gi cu. Nu khung ngang hoc vch ngang u l cho th thnh phn dc ca lc do b phn cho truyn ti phi c xem xt. Khi cc trc u cho hn 20oC, cc khung ngang trung gian phi trc giao vi cc cu kin chnh. Nu cc tr u cho th cc khung ngang khng cn phi song song vi ng ca cc gi.

Cc vch ngang u phi c thit k cho cc lc v s mo hnh truyn n t mt cu v mi ni mt cu. Cc mmen u ca cc vch ngang phi c xem xt trong thit k c s lin quan gia thnh phn dc v cc vch ngn.

6.7.4.3. Dm thng c mt ct hp Phi lm cc vch ngang hoc cc khung ngang bn trong cc tit din hnh hp ti m tr chu c s xoay ngang, s chuyn v v s cong vnh, v phi c thit k truyn cc mmen xon v cc lc ngang t hp ti cc gi.

Nu lm vch ngang tm c s lin tc hoc chu c cc lc ko pht sinh bi cc cu kin cu, th vch ngn phi c lin kt vo cc bn bng v cc bn cnh ca mt ct hp.

Cn lm cc ca qua v phi rng c th. Tc ng ca cc ca qua ln cc ng sut trong cc vch ngn cn c nghin cu xc nh xem c cn gia c khng.

Phi thc hin nghin cu vic b cc vch ngang hoc cc khung ngang vnh cu bn trong hoc gia cc mt ct nhiu hp thp thng c thit k ph hp vi cc iu khon i vi cc mt ct nhiu hp quy nh trong iu 6.11.1.1.

Trong cc mt ct hp n phi lm cc vch ngang hoc cc khung ngang trung gian bn trong v phi b tr khong cch hn ch mo vn ca mt ct ngang.6.7.4.4. Gin v vmPhi lm cc vch ngang cc lin kt vo cc dm sn v cc lin kt khc hoc cc im t cc ti trng tp trung. Cng c th lm cc vch ngn bn trong gi s dng thng ca b phn.

Cc bn tit im gn cht gi u ca gin phi c lin kt bng vch ngn. Cc bn bng ca b gi cn c lin kt bng vch ngang ni no c th thc hin c.

Nu u ca bn bn bng hoc bn ph di bng 1200 mm hoc hn tnh t im giao ct ca cc b phn, th phi lm vch ngang gia cc bn tit im gn cc b phn chnh.

6.7.5. Lin kt tng cng ngang (H ging ngang)

6.7.5.1. Tng qutNhu cu (Yu cu) ging ngang phi c nghin cu cho tt c cc giai on thi cng d kin v cho trng thi cui cng khi khai thc cng trnh.

ch no cn th nn t ging ngang trong hoc gn mt phng ca bn cnh hoc thanh m gin cn ging. Vic nghin cu yu cu i vi h ging ngang phi bao gm, nhng khng b hn ch :

Truyn cc ti trng gi ngang n cc gi nh quy nh trong iu 4.6.2.7, v

Truyn cc ti trng ngang nh quy nh trong iu 4.6.2.8 , v

Kim sot cc bin dng trong qu trnh ch to, lp rp v t thng b vo v tr.

H lin kt tng cng ngang cn cho cc trng thi khng phi l trng thi cui cng th c th c tho i.

Nu h ging ngang lu di c tnh n trong m hnh kt cu s dng xc nh cc tc dng lc, th h ny phi c thit k cho tt c cc trng thi gii hn c th p dng c. Phi p dng cc quy nh ca cc iu 6.8.4 v 6.9.3.

Cc bn lin kt cho h lin kt tng cng ngang phi tha mn cc yu cu quy nh trong iu 6.6.1.3.2.

Khi h lin kt tng cng ngang c thit k cho chu ti ng t phi p dng cc quy nh iu 4.6.2.8.

6.7.5.2. Dm thng c mt ct ch I

ch no cn thit th h ging ngang phi c t trong cc khoang bn ngoi. Cc bn cnh gn vo cc bn mt cu c cng ging bn cnh th khng cn h ging ngang na.

Nhu cu lin kt ngang trong cc vng mmen un m ca cc dm lin tc m bo n nh trong khi lp rp phi c nghin cu.

6.7.5.3. Dm thng c mt ct hp Nhu cu (Yu cu) ging ngang gia cc bn cnh ca cc hp ring l phi c nghin cu bo m rng cc bin dng ca mt ct hp u c kim sot y trong khi ch to, lp rp v t mt cu b tng.

H ging ngang pha trn phi c thit k chu dng ct trong mt ct trc khi bo dng b tng mt cu. Lc sinh ra trong h ging do un ca hp cng phi c xt n.

Nu h lin kt c gn ni vo cc bn bng, th din tch mt ct ngang ca hp v dng ct phi gim i phn nh v tr thc t ca h lin kt, v phi thc hin bin php truyn cc lc t h lin kt n bn cnh trn.

6.7.5.4. GinCc nhp gin chy di cc nhp gin chy trn phi c h ging ngang trn v ging ngang di. Nu s dng h ging ngang dng ch X th mi cu kin c th coi l lm vic ng thi hai hng ko v nn nu chng p ng c cc yu cu mnh i vi c hai phn chu ko v chu nn. Cc cu kin cn c lin kt cc ch giao nhau ca chng.

Cu kin lm h ging ngang cho cc thanh m chu nn cn lm cng cao cng tt v lin kt vo c hai bn cnh.

Cc lin kt dm sn cn c b tr sao cho h ging ngang s gn ni c dm sn v cu kin phn chu lc chnh. ch no h ging ngang giao vi mi ni hnh thnh bi dm sn v cu kin dc chnh, th cu kin ging ngang phi c lin kt vo c hai b phn trn.

6.7.6. Cht

6.7.6.1. V trCc cht phi b tr sao cho gim thiu c cc tc dng ca lc do lch tm.

6.7.6.2. Sc khng6.7.6.2.1. Un v ct kt hp

Cc cht chu un v ct kt hp phi c cn xng tha mn:

(6.7.6.2.1-1)

trong :

D = ng knh ca cht (m)

Mu = mmen do cc ti trng tnh ton (N-mm)

Vu = lc ct do cc ti trng tnh ton (N)

Fy = cng chy nh nht quy nh ca cht (MPa)

(f = h s sc khng un nh quy nh trong iu 6.5.4.2

(v = h s sc khng ct nh quy nh trong iu 6.5.4.2

Mmen Mu, v lc ct Vu cn c ly cng mt ct thit k dc theo cht.

6.7.6.2.2. p mt

Sc khng p mt tnh ton trn cc cht phi c ly nh sau:

(RpB)r = (b (RpB)n (6.7.6.2.2-1)

trong :

(RpB)n = 1,5 t DFy (6.7.6.2.2-2)

y:

t = chiu dy ca bn (mm)

D = ng knh ca cht (mm)

(b = h s sc khng p mt theo quy nh trong iu 6.5.4.2

6.7.6.3. Kch thc ti thiu ca cht i vi cc thanh c tai treo

ng knh ca cht D, khng c nh hn:

(6.7.6.3-1)

trong :

Fy = cng chy do nh nht quy nh ca cht (MPa)

b = chiu rng ca thn ca thanh c tai treo (mm).

6.7.6.4. Cht v ai c ca chtCc cht phi c chiu di bo m s p mt hon ton ca tt c cc phn lin kt trn thn vn ca cht. Cht phi c bo m ng v tr bng:

Cc ai c hnh lc gic tin lm vo

Cc ai c cng hnh lc gic vi cc vng m, hoc

Nu cc cht c khoan l xuyn qua th u cht c ngn gi bng cc cm thanh cht

Cc ai c ca cht hoc thanh cht phi l cc sn phm c rn hoc thp v phi bo m ng v tr bng cc cht hm xuyn qua cc ren, hoc bng mi cc ren. Cc ai c kha sn c th trng c th c s dng thay cho s mi cc ren hoc dng cc cht hm.

6.8. cu kin chu ko

6.8.1. Tng qut

Cc cu kin v cc mi ni i u chu lc ko dc trc phi nghin cu i vi hai iu kin:

Chy ca mt ct nguyn, th d, Phng trnh 6.8.2.1-1, v

t ca mt ct thc, th d, Phng trnh 6.8.2.1-2.

Khi xc nh mt ct thc cn phi xt n:

Din tch nguyn, t din tch ny s khu tr i hoc p dng cc h s trit gim thch hp,

Khu tr tt c cc l trong mt ct ngang thit k,

Hiu chnh cc khu tr l bulng i vi quy tc b tr ch chi c quy nh trong iu 6.8.3,

p dng h s trit gim U, quy nh trong iu 6.8.2.2, i vi cc b phn v iu 6.13.5.2 i vi cc bn tp ni v cc cu kin tp ni khc tnh n s tr trt v

p dng h s din tch hiu dng ln nht 85% i vi cc bn tp ni v cc cu kin tp ni khc quy nh trong iu 6.13.5.2

Cc cu kin chu ko phi tha mn cc yu cu v mnh nh quy nh trong iu 6.8.4 v cc yu cu v mi ca iu 6.6.1. Cng ct khi phi c nghin cu cc lin kt nh quy nh trong iu 6.13.4.

6.8.2. Sc khng ko

6.8.2.1. Tng qutSc khng ko tnh ton, Pr, phi ly ci nh hn trong hai gi tr m cc Phng trnh 1 v 2 cho:

Pr = (y Pny = (y Fy Ag (6.8.2.1-1)

Pr = (u Pnu = (u Fu An U (6.8.2.1-2)

trong :

Pny = sc khng ko danh nh i vi s chy trong mt ct nguyn (N)

Fy = cng chy (MPa)

Ag = din tch mt ct ngang nguyn ca b phn (mm2)

Pnu = sc khng ko danh nh i vi t gy trong mt ct thc (N)

Fu = cng chu ko (MPa)

An = din tch thc ca b phn theo quy nh trong iu 6.8.3 (mm2)

U = h s trit gim tnh b cho tr trt, 1,0 i vi cc thnh phn trong cc tc dng lc c truyn ti tt c cc cu kin, v theo quy nh trong iu 6.8.2.2 i vi cc trng hp khc

(y = h s sc khng i vi chy do ca cc b phn chu ko theo quy nh trong iu 6.5.4.2(u = h s sc khng i vi t gy ca cc b phn chu ko theo quy nh trong iu 6.5.4.26.8.2.2. H s trit gim, UTrong trng hp thiu cc th nghim hoc phn tch chnh xc hn, cc h s trit gim y c th c s dng tnh b cho s tr trt trong cc lin kt.

H s trit gim, U, cho thp hnh I cn v cc thanh ch T ct t thp hnh I, chu ti trng truyn trc tip n mt s, phn t thi m khng phi l tt c, c th c ly nh sau:

i vi cc lin kt ch c cc mi hn ngang u:

(6.8.2.2-1)

H s trit gim, U, cho c cc cu kin loi khc chu ti trng truyn n mt s, phn t thi m khng phi l tt c, qua cc lin kt bulng vi ba hoc trn ba bulng mi ng trong phng ca ti trng, hoc cc lin kt hn, tr cc trng hp c ch gii di y, c th c ly nh sau:

U = 0,85.

H s trit gim, U, cho cc lin kt c cc ng hn dc, dc theo c hai mp ca phn c lin kt, c th c ly nh sau:

Nu L > 2W, th U = 1,0

Nu 2W > L > 1,5W, th U = 0,87

Nu 1,5W > L > W, th U = 0,75

trong :

Ane = din tch thc chu ti trng trong phm vi chiu di lin kt ca cc cu kin (mm2)

Agn = din tch thc nh nht ca b phn ngoi chiu di lin kt (mm2)

W = chiu rng ca cu kin lin kt (mm)

L = chiu di ng hn (mm)

6.8.2.3. Ko v un kt hpCu kin chu ko v un kt hp phi tha mn cc Phng trnh 1 v 2:

Nu , th (6.8.2.3-1)

Nu , th (6.8.2.3-2)

trong :

Pr =sc khng ko tnh ton theo quy nh trong iu 6.8.2.1 (N)

Mrx, Mry = sc khng un tnh ton theo cc trc X v Y, tng ng, c quy nh trong iu 6.10.4 v 6.12 (N-mm)

Mux, Muy = cc mmen theo cc trc x v y, tng ng, do cc ti trng tnh ton gy ra (N-mm)

Pu = hiu ng lc dc trc do cc ti trng tnh ton gy ra (N)S n nh ca bn cnh chu ng sut nn thc do ko v un phi c nghin cu v on cc b.6.8.3. Din tch thc

Mt ct thc An ca mt cu kin l tng cc tch s ca chiu dy v chiu rng thc nh nht ca mi b phn. B rng khu tr tt c cc l chun, ngoi c v c khot trng phi c ly bng gi tr ln hn kch c l quy nh trong iu 6.13.2.4.2.

Phi xc nh chiu rng thc i vi tng chui cc l v trin khai ngang qua cu kin v dc theo bt c tuyn ngang, xin hay ng ch chi bt k no.Chiu rng thc i vi mi dy phi c xc nh bng chiu rng ca cu kin tr i tng cc chiu rng ca tt c cc l trong dy v cng thm lng s2/4g cho mi khong cch gia cc l tip lin nhau trong dy, trong :

s = bc ca bt k hai l tip lin nhau (mm)

g = kch c ca cng hai l (mm)

i vi cc thp gc, kch c i vi cc l trong cc cnh k i din phi bng tng cc kch c t lng ca cc thp gc tr i chiu dy.

6.8.4. T s mnh gii hn

Cc b phn chu ko khc vi cc thanh ko, thanh c tai treo, dy cp v cc bn phi tha mn cc yu cu mnh quy nh y:

i vi cc cu kin chnh chu ng sut i du ................................( / r ( 140

i vi cc cu kin chnh khng chu cc ng sut i du ..............( / r ( 200

i vi cc cu kin ging ................................................................ .... ( / r (. 240

trong :

( = chiu di khng ging (mm)

r = bn knh hi chuyn nh nht (mm)

6.8.5. Cc cu kin t hp

6.8.5.1. Tng qutCc phn b chnh ca cc cu kin chu ko c t hp t thp hnh cn hoc hn phi c lin kt hoc bng cc bn lin tc c hoc khng khot l, hoc bng cc bn ni c hoc khng c thanh np. Cc lin kt hn gia thp hnh v cc bn thp phi lin tc. Cc lin kt bulng gia thp hnh v cc bn thp phi tun theo cc quy nh ca iu 6.13.2

6.8.5.2. Cc bn khot lT l ca chiu di theo phng ca ng sut vi chiu rng ca cc l khng c vt qu 2,0.

Khong cch tnh gia cc l theo phng ca ng sut khng c nh hn khong cch ngang gia cc ng bulng hoc ng hn gn nht. Khong cch tnh gia u ca bn v l th nht khng c nh hn 1,25 ln khong cch ngang gia cc bulng hoc ng hn.

Chu vi ng trn ca cc l phi c bn knh ti thiu l 38 mm.

Cc chiu rng khng c chng cc mp ca cc l c th gi nh l gp phn vo din tch thc ca b phn.

ch no cc l c b tr so le theo cc bn khot l ngc nhau, din tch thc ca b phn phi c xem nh cng din tch ca mt ct c cc l trong cng mt phng ngang.

6.8.6. Cc thanh c tai treo

6.8.6.1. Sc khng tnh tonSc khng tnh ton ca thn ca thanh c tai treo phi ly nh quy nh trong Phng trnh 6.8.2.1-1.

6.8.6.2. S cn iCc thanh c tai treo phi c chiu dy ng u, khng nh hn 14 mm hoc ln hn 50 mm.

Bn knh chuyn tip gia u v thn ca thanh c tai treo khng c nh hn chiu rng ca u ti ng tim ca l cht.

Chiu rng thc ca u ti ng tim ca l cht khng c nh hn 135% chiu rng cn thit ca thn.

Kch thc thc ca u bn ngoi l cht ly theo phng dc khng c nh hn 75% ca chiu rng ca thn.

Chiu rng ca thn khng c vt qu tm ln chiu dy ca n.

Tim ca l cht phi c t trn trc dc ca thn ca thanh c tai treo. ng knh l cht khng c ln hn ng knh cht 0,8 mm.

i vi cc loi thp c cng chy do nh nht ch nh ln hn 480 MPa, ng knh l khng c vt nm ln chiu dy ca thanh c tai treo.

6.8.6.3. m chnCc thanh c tai treo ca mt b phi i xng i vi mt phng trung tm ca cu kin v cng song song cng tt. Chng phi c ngn gi chng li s chuyn ng nm ngang trn cc cht v chng li s cong vnh nm ngang do s cho ca cu.

Cc thanh c tai treo phi c b tr cc thanh k trong cng khoang c tch ra t nht l 14 mm. Phi c cc vng m m mi khe h gia cc thanh c tai treo k nhau trn mt cht. Cc thanh cho giao nhau u khng xa khng tr ngi ln nhau mi lc th phi c kp cht li cng nhau ch giao nhau.

6.8.7. Cc bn lin kt cht

6.8.7.1. Tng qut ni no c th c th nn trnh cc bn lin kt cht.

Cc quy nh ca iu 6.8.2.1 phi c tha mn.

6.8.7.2. Bn cht

Sc khng p mt tnh ton trn cc bn cht, Pr, phi ly nh sau:

Pr = (b Pn = (b Ab Fy(6.8.7.2-1)

y:

Pn = sc khng p mt danh nh (N)

Ab = din tch p mt chiu ln bn (mm2)

Fy = cng chy do nh nht quy nh ca bn (MPa)

(b = h s sc khng i vi p mt quy nh trong iu 6.5.4.2.

Bn chnh c th c tng cng trong vng l bng gn vo cc bn cht gia tng chiu dy ca tm bn chnh.

Nu s dng bn cht, phi b tr gim thiu lch tm ca hot ti v c gn vo bn chnh bng cc ng hn hoc cc bulng truyn cc lc p mt t cc bn cht vo bn chnh.

6.8.7.3. S cn iT hp din tch thc ca bn chnh v cc bn cht trn mt mt ct ngang xuyn qua ng tim ca l cht khng c nh hn 1,4 ln din tch thc yu cu ca bn chnh xa l.

Din tch thc t hp ca bn chnh v cc bn cht xa l cht, ly theo phng dc, khng c nh hn din tch thc yu cu ca bn chnh xa l cht.

Tim ca l cht phi c t trn trc dc ca bn chnh. ng knh l cht khng c ln hn ng knh cht l 0,8 mm.

i vi cc thp c cng chy ti thiu quy nh ln hn 480 MPa, ng knh l khng c vt qu nm ln chiu dy t hp ca bn chnh v cc bn cht.

Chiu dy t hp ca bn chnh v cc bn cht khng c nh hn 12% ca chiu rng thc t mp l n mp ca bn hoc cc bn. Chiu dy ca bn chnh khng c nh hn 12% ca chiu rng yu cu xa l.

6.8.7.4. m chnCc cu kin lin kt cht phi c ngn gi chng li s chuyn ng nm ngang trn cht v chng li s cong vnh do s cho ca cu.

6.9. cu kin chu nn

6.9.1. Tng qut

Cc quy nh ca iu ny c p dng cho cc cu kin thp lin hp v khng lin hp c mt ct khng i vi t nht mt mt phng i xng v chu hoc nn dc trc hoc nn dc trc v un kt hp i vi trc i xng.

Cc vm cn phi tha mn cc yu cu ca iu 6.14.4.

Cc thanh m chu nn ca cc gin chy gia cn phi tha mn cc yu cu ca iu 6.14.2.9.

6.9.2. Sc khng nn

6.9.2.1. Nn dc trc

Sc khng tnh ton ca cc cu kin trong chu nn, Pr, phi c ly nh sau:

Pr = (c Pn (6.9.2.1.-1)

trong :

Pn = sc khng nn danh nh theo quy nh cc iu 6.9.4 v 6.9.5 (N)

(c = h s sc khng i vi nn theo quy nh trong iu 6.5.4.2

6.9.2.2. Nn dc trc v un kt hp

Ti trng nn dc trc, Pu, v cc mmen xy ra ng thi, Mux v Muy, tnh ton i vi cc ti trng tnh ton bng cc phng php gii tch n hi phi tha mn mi quan h sau y:

Nu

, th

(6.9.2.2-1)

Nu

, th (6.9.2.2-2)

Pr = sc khng nn tnh ton theo quy nh trong iu 6.9.2.1 (N)

Mrx = sc khng un tnh ton theo trc x theo quy nh trong cc iu 6.10.6.11 v 6.12 (N-mm)

Mry= sc khng un tnh ton theo trc y theo quy nh trong cc iu 6.10.6.11 v 6.12 (N-mm)

Mux= mmen un tnh ton theo trc x c tnh ton theo quy nh bn di (N-mm)

Muy= mmen un tnh ton theo trc y c tnh ton theo quy nh bn di (N-mm)

Cc mmen Mux v Muy theo cc trc i xng, c th c xc nh bng hoc:

S phn tch n hi bc hai, c tnh n khuych i mmen gy ra bi ti trng trc tnh ton, hoc

S iu chnh gn ng mt bc nh quy nh trong iu 4.5.3.2.2b.

6.9.3. T s mnh gii hn

Cc cu kin chu nn phi tha mn cc yu cu ca mnh y:

i vi cc b phn chnh:

i vi cc b phn lin kt:

trong :

K = h s chiu di hiu dng quy nh trong iu 4.6.2.5

= chiu di khng ging (mm)

r = bn knh hi chuyn nh nht (mm)

i vi ring iu ny, bn knh hi chuyn quay c th tnh trn mt mt ct tng tng b qua phn ca din tch ca mt thnh phn, min l:

Kh nng ca thnh phn cn c trn din tch v bn knh quay thc t ln hn cc ti trng tnh ton, v

Kh nng ca thnh phn tng tng cn c trn din tch trit gim v bn knh quay tng ng cng ln hn cc ti trng tnh ton.

6.9.4. Cc cu kin khng lin hp

6.9.4.1. Sc khng nn danh nhi vi cc cu kin tha mn cc yu cu chiu rng/chiu dy ch nh trong iu 6.9.4.2, sc khng nn danh nh, Pn, phi c ly nh sau:

Nu ( ( 2,25 th Pn = 0,66( FyAs (6.9.4.1-1)

Nu ( > 2,25 th Pn = (6.9.4.1-2)

vi:

(6.9.4.1-3)

trong :

As = din tch mt ct ngang nguyn (mm2)

Fy = cng chy (MPa)

E = mun n hi (MPa)

K= h s chiu di hiu dng quy nh trong iu 4.6.2.5.

( = chiu di khng ging (mm)

rs = bn knh hi chuyn theo mt phng bng (mm)

i vi cc cc thp ch di ti trng trc, Pn khng c vt qu tr s sau y:

i vi cc cc H .................................................................................. 0,78 Fy As i vi cc cc ng .............................................................................. 0,87 Fy As6.9.4.2. Cc t s chiu rng/chiu dy gii hn i vi nn dc trc

mnh ca cc bn phi tha mn:

(6.9.4.2.1)

trong :

k = h s on ca bn theo quy nh trong Bng 1

b = chiu rng ca bn nh quy nh trong Bng 1 (mm)

t = chiu dy bn (mm)

Chiu dy vch ca cc ng phi tha mn:

i vi cc ng trn :

(6.9.4.2-2)

i vi cc ng ch nht :

(6.9.4.2-3 )

trong :

D = ng knh ng (mm)

b = chiu rng mt (mm)

t = chiu dy ng (mm)

i vi cc cu kin khi thit k c dng cc phng trnh ca iu 6.9.2.2, Fy nh s dng y, c th c thay th bi ng sut nn tnh ton ln nht do ti trng dc trc tnh ton v mmen un xy ra ng thi.

Bng 6.9.4.2.1 - Cc t s chiu rng - chiu dy gii hn

Cc bn c dc mt mpKb

0,56 Chiu rng na bn cnh ca cc mt ct I

Chiu rng ton bn cnh ca cc thp (

Cc bn cnh v cc cnh nh ra hoc cc bn Khong cch gia mp t do v hng bulng th nht hoc cc ng hn trong cc bn

Ton chiu rng ca cnh bn nh ra i vi cc i thp gc trong tip xc lin tc

Cc thn ca thp T cn0,75 Ton chiu cao ca T

Cc cu kin nh ra khc0,45 Ton chiu rng ca cnh bn nh ra i vi thanh chng thp gc n hoc thanh chng thp gc i vi tm ngn

Ton chiu rng nh ra i vi cc cu kin khc

Cc bn c dc hai mpkb

Cc bn cnh hp v cc bn tp1,40 Khong cch tnh gia cc bn bng tr i bn knh gc trong trn mi bn i vi cc bn cnh hp

Khong cch gia cc ng hn hoc bulng i vi cc bn ph bn cnh

Cc bn bng v cc cu kin bn khc1,49 Khong cch tnh gia cc bn cnh tr i cc bn knh ng hn i vi cc bn bng ca cc dm cn

Khong cch tnh gia cc thanh mp i vi tt c cc cu kin khc

Cc bn tp c khot l1,86 Khong cch tnh gia cc thanh mp

6.9.4.3. Cc cu kin t hp6.9.4.3.1. Tng qut

Phi p dng cc quy nh ca iu 6.9.4.2. T s mnh ca cc cu kin gia cc bulng lin kt khng c nhiu hn 75% ca t s mnh khng ch ca b phn.

6.9.4.3.2. Cc bn khot l

Cc bn khot l phi tha mn cc yu cu ca cc iu 6.9.4.2 v 6.8.5.2 v phi c thit k cho tng lc ct do cc ti trng tnh ton v mt lc ct ph ly nh sau:

(6.9.4.3.2-1)

trong :

V = lc ct ph thm (N)

Pr = sc khng nn tnh ton quy nh trong cc iu 6.9.2.1 v 6.9.2.2 (N)

= chiu di cu kin (mm)

r = bn knh hi chuyn theo trc thng gc n bn khot l (mm)

Fy = cng chy (MPa)

6.9.5. Cc cu kin lin hp

6.9.5.1. Sc khng nn danh nh

Cc quy nh ca iu ny p dng cho cc ct lin hp khng chu un. Cc quy nh ca iu 6.12.2.3 p dng cho cc ct lin hp chu un.

Sc khng nn danh nh ca ct lin hp tha mn cc quy nh ca iu 6.9.5.2 phi ly nh sau:

Nu ( ( 2.25 th Pn = 0.66( Fe As(6.9.5.1-1)

Nu ( > 2.25 th Pn =

(6.9.5.1-2)

vi :

(6.9.5.1-3)

Fe = Fy+ C1Fyr + C2

(6.9.5.1-4)

(6.9.5.1-5)

trong :

As = din tch mt ct ngang ca mt ct thp (mm2)

Ac = din tch mt ct ngang ca b tng (mm2)

Ar = tng din tch mt ct ngang ca ct thp dc (mm2)

Fy = cng chy nh nht quy nh ca mt ct thp (MPa)

Fyr = cng chy nh nht quy nh ca ct thp dc (MPa)

= cng nn 28 ngy nh nht quy nh ca b tng (MPa)

E = mun n hi ca thp (MPa)

=chiu di khng ging ca ct (mm)

K = h s chiu di hiu dng theo quy nh trong iu 4.6.2.5

n = t s mun ca b tng theo quy nh trong iu 6.10.5.1.1b

rs = bn knh hi chuyn ca mt ct thp trong mt phng un, nhng khng nh hn 0,3 ln chiu rng ca b phn lin hp trong mt phng un i vi cc thp hnh c bc b tng lin hp (mm)

C1, C2, C3 = hng s ct lin hp c quy nh trong Bng 1.

Bng 6.9.5.1-1 - Cc hng s ct lin hp

Cc ng c nhi yCc thp hnh c bc

C11,00,70

C20,850,60

C30,400,20

Khi xc nh s khuych i mmen i vi cc b phn lin hp chu nn dc trc v un kt hp theo s iu chnh gn ng mt bc quy nh trong iu 4.5.3.2.2b, phi p dng phng trnh sau y:

Pe = (6.9.5.1-6)

6.9.5.2. Cc gii hn6.9.5.2.1. Tng qut

Sc khng nn phi c tnh ton ph hp vi iu 6.9.5.1, nu din tch mt ct ngang ca mt ct thp gm t nht 4% tng din tch mt ct ngang ca b phn.

Sc khng nn phi c tnh ton nh l ct b tng ct thp trong Phn 5, nu din tch mt ct ngang ca thp hnh hoc ng nh hn 4% tng din tch mt ct ngang.

Cng nn ca b tng phi gia 20 MPa v 55 MPa.

Cng chy ca mt ct thp v ct thp dc s dng tnh sc khng nn danh nh phi khng vt qu 420 MPa.

S truyn tt c ti trng trong ct lin hp phi c xem xt trong thit k cc thnh phn .

Mt ct ngang phi c t nht mt trc i xng

6.9.5.2.2. Cc ng nhi y b tng

Cc yu cu v chiu dy ca vch i vi cc ng khng nhi quy nh trong iu 6.9.4.2 phi p dng cho cc ng lin hp nhi y b tng.

6.9.5.2.3. Cc thp hnh bc b tng

Cc thp hnh bc b tng phi c tng cng bng ct thp dc v ngang. Ct thp phi tun theo cc quy nh ca iu 5.7.4.6, tr khong cch thng ng ca cc thanh ging ngang phi khng c vt qu tr s nh nht ca:

16 ln ng knh thanh thp dc

48 ln ng knh thanh ging hoc

0,5 kch thc bn nh nht ca cu kin lin hp

Nhiu thp hnh trong cng mt ct ngang ca mt ct lin hp phi c lin kt vi nhau bng ai v cc bn ging phng on cc thp hnh ring l trc khi b tng ng cng.

6.10. Cc mt ct ch ( chu un

6.10.1. Tng qut

Cc iu khon mc ny c p dng cho cc mt ct ch ( thng chu un bng thp cn hoc t hp i xng i vi trc thng ng nm trong mt phng ca bn bng dm.

Cc mt ct lai hoc phi hp gm mt bn bn bng c cng chy nh nht quy nh thp hn cng mt hoc c hai bn cnh c th c thit k theo cc quy nh ny. Cho php dng cc mt ct m thp bn bng c cng cao hn thp cc bn cnh nhng khng c coi l mt ct lai.

Cc iu khon ca cc mc ny c p dng cho cc mt ct c chc hoc khng c chc v cc mt ct lin hp hoc khng lin hp.

Cc cu kin chu un phi c thit k theo :

Sc khng un theo trng thi gii hn cng c quy nh trong mc 6.10.4

Kim tra trng thi gii hn s dng i vi vng di hn c quy nh trong Mc 6.10.5.

Trng thi gii hn mi v t gy ca cc chi tit c quy nh theo Mc 6.5.3 v cc yu cu v mi i vi cc bn bng dm theo quy nh Mc 6.10.6.

Sc khng ct theo trng thi gii hn cng c quy nh theo Mc 6.10.7 v

Tnh kh thi ca kt cu c quy nh theo 6.10.3.2.

C th xem xt cc iu khon tu chn v vng theo Mc 2.5.2.6.2.

6.10.2. Cc gii hn trong vic xc nh kch thc mt ct.

Cn c trn vic nghin cu v un, cc t l cu to ca mt ct ch I phi tho mn cc iu sau y trong tt c cc giai on thi cng v trong trng thi cui cng.

Trong mc 6.10.2.2, fc v Dc phi c ly sao thch hp vi iu kin ang nghin cu.

6.10.2.1. Cc t l cu to chung

Cc cu kin un phi c cu to theo t l sao cho:

( 6.10.2.1-1)

trong :

Iy= m men qun tnh ca mt ct thp i vi trc thng ng trong mt phng ca bn bng (mm4)

Iyc= m men qun tnh ca bn cnh chu nn ca mt ct thp quanh trc ng trong mt phng cu bn bng (mm4).

6.10.2.2. mnh ca bn bng.

Bn bng dm phi c cu to sao cho:

Khi khng c g tng cng dc

(6.10.2.2.1).

Khi c g tng cng dc

(6.10.2.2-2)

trong :

Dc= chiu cao ca bn bng chu nn trong phm vi n hi (mm)

fc= ng sut bn cnh chu nn do lc tnh ton (Mpa)

6.10.3. p dng

6.10.3.1. Cc mt ct lin hp

Cc mt ct lin hp c nh ngha l nhng mt ct gm mt bn mt b tng lin kt vi mt mt ct thp bng lin kt chng ct ph hp vi iu 6.10.7.4 v c th p dng cho cc h bn mt khc c chng minh m bo c tc dng lin hp v chng un ngang.

6.10.3.1.1. Cc ng sut

6.10.3.1.1a. Trnh t cht ti trng

ng sut n hi mt v tr bt k trn mt ct lin hp do ti trng tc dng gy ra phi bng tng s cc ng sut gy ra bi cc lc tc dng ring r tc dng vo:

Phn thp

Mt ct lin hp ngn hn v

Mt ct lin hp di hn.

Ti trng di hn tc dng, trc khi bn t c 75% fc , c gi thit phi do mt ct thp chu n c. Ti trng di hn v hot ti tc dng sau khi bn t c 75% fc c gi thit phi do mt ct lin hp chu. i vi cc cng trnh c tr phi gi thit ton b ti trng di hn tc dng sau khi bn t c 75% fc v trong ti liu hp ng phi ch r nh vy.

6.10.3.1.1b. un dng

Khi tnh ton cc ng sut un phi xt mt ct lin hp gm mt ct thp v mt ct chuyn i ca bn b tng vi b rng hiu dng.

i vi cc ti trng tm thi, gi thit chng tc dng vo mt ct lin hp ngn hn v mt ct bn khi chuyn i phi dng t s m un ngn hn, n.

i vi cc ti trng di hn, gi thit chng tc dng vo mt ct lin hp di hn mt ct bn khi chuyn i th dng t s m un bng 3n.

i vi b tng c khi lng ring thng thng, t s mun c th ly nh sau:

16 ( fc ( 20; n = 10

20 ( fc ( 25; n = 9

25 ( fc ( 32; n = 8

32 ( fc ( 41; n = 7

41 ( fc ; n = 6

6.10.3.1.1c. un m

tnh ton cc ng sut do m men gy ra, i vi c m men lin hp di hn ln ngn hn, mt ct lin hp phi bao gm c mt ct thp v ct thp theo phng dc trng phm vi chiu rng hiu dng ca bn.

6.10.3.1.1d. Chiu rng hiu dng ca bn

Nu khng c thng tin tt hn, phi p dng cc qui nh ca iu 4.6.2.6.

6.10.3.1.2. M men chy

M men chy My mt mt ct lin hp phi ly bng tng cc m men tc dng ring l vo phn thp v vo cc mt ct lin hp ngn hn v di hn gy trng thi chy u tin mt trong hai bn cnh thp, khi khng xt n chy hnh thnh bn bng ca mt ct lai.

6.10.3.1.3. M men do

Mp phi c tnh ton bng m men u tin ca lc do i vi trc trung ho do. tnh ton cc lc do trong cc phn thp ca mt ct lin hp, phi dng cng chy tng ng cho c bn cnh, bn bng v ct thp. Lc do trong cc phn b tng chu nn ca mt ct lin hp c th da trn khi ng sut ch nht nh ch dn trong iu 5.7.2.2. v b qua b tng chu ko.

V tr ca trc trung ho do phi c xc nh theo iu kin cn bng m khng c lc dc trc thun tu.

6.10.3.1.4. Chiu cao ca bn bng chu nn.

6.10.3.1.4a. Ti m men n hi

i vi cc mt ct chu un dng, chiu cao ca bn bng chu nn Dc ti m men n hi thit k bng chiu cao m trn tng i s ca cc ng sut trong thp cc mt ct lin hp di hn v lin hp ngn hn do cc tnh ti v hot ti gy ra cng vi xung kch u l ng sut nn. i vi cc mt ct chu un m, c th tnh ton Dc cho mt ct bao gm dm thp cng vi ct thp theo phng dc.

6.10.3.1.4b Ti m men do

Chiu cao ca bn bng chu nn ti m men do Dcp c th c xc nh nh sau:

i vi cc mt ct chu un dng, khi trc trung ho do qua bn bng, Dcp c ly l:

(6.10.3.1.4b-1)

trong :

Dcp= chiu cao bn bng chu nn ti m men do (mm).

D= chiu cao bn bng (mm).

As= din tch bn.

At= din tch bn cnh chu ko (mm2).

Fyc= cng chy nh nht quy nh ca bn cnh chu nn (MPa).

Fyc = cng chy nh nht quy nh ca ct thp dc trong mt ct (Mpa)

Fyt= cng chy nh nht quy nh ca bn cnh chu ko (MPa).

Fyw= cng chy nh nht quy nh ca bn bng (MPa).

Fc= cng chu nn 28 ngy quy nh ca b tng (MPa).

i vi tt c cc mt ct chu un dng, Dcp phi ly bng 0 v yu cu v mnh ca bn bng trong mt ct c chc iu 6.10.4.1.2 phi coi l tho mn.

i vi cc mt ct chu un m khi c trc trung ho do i qua bn bng:

(6.10.3.1.4b-2)

i vi cc mt ct khc chu un m, Dcp phi ly bng D.

6.10.3.2. Yu cu v cu to i vi cc mt ct lin hp

6.10.3.2.1. Tng qut

m bo yu cu v cu to i vi cc mt ct lin hp trng thi cui cng nhng khng lin hp trong qu trnh thi cng khi nghin cu phi c coi l cc mt ct khng lin hp cc giai on khc nhau theo trnh t lp t mt cu qua vic s dng t hp ti trng thch hp trong Bng 3.4.1-1 tnh ton. Cc c trng hnh hc, chiu di ging, v ng sut c s dng trong tnh ton sc khng un danh nh theo mc ny ch p dng i vi mt ct thp di tc dng ca ti trng thi cng tnh ton. Cc thay i v ti trng, cng v h ging trong cc giai on b tng phi c xem xt.

6.10.3.2.2. Sc khng un danh nh

Phi tin hnh nghin cu v cu to ca cc dm lin hp theo cc quy nh ca iu 6.10.4.1.4 v mnh bn cnh chu nn ca mt ct khng c chc.

Cc dm lin hp trong giai on thi cng, khi cn cha c lin hp phi tho mn cc yu cu nu trong iu 6.10.2.2 v mnh ca bn bng khng c chc theo truyn thng.

6.10.3.2.3. Sc khng ct danh nh

i vi cc bn bng ca cc mt ct ng cht, c cc sn tng cng ngang v c hoc khng c cc sn tng cng dc, sc khng ct danh nh nghin cu v trnh t lp mt cu phi l:

Vn = C Vp

trong :

C = t s ca ng sut gy mt n nh trn tr s cng chy do khi chu ct theo quy nh bn cnh 6.10.7.3.3a.

Vp= kh nng chu ct do c quy nh iu 6.10.7.3.3a (N)

6.10.3.3. Cc mt ct khng lin hp

Khi xt v mt k thut c tnh kh thi, phi dng cc kt cu lin hp.

i vi cc mt ct thp khng c cc neo chng ct c quy nh ph hp vi iu 6.10.7.4 cho php xem l nhng mt ct khng lin hp.

6.10.3.3.1. M men chy v m men do

Phi tnh m men chy My ca mt mt ct khng lin hp l m men cn thit gy ra chy u tin mt trong bn cnh khi khng xt n bt k s chy no bn bng ca mt ct lai.

M men do Mp ca mt mt ct khng lin hp phi ly bng tng m men ca ton b s phn phi ng sut do tc dng vo mt ct.

6.10.3.3.2. Chiu cao ca bn bng chu nn ti m men do

Chiu cao ca bn bng ti m men do phi c xc nh nh di y:

Nu: FywAw FycAc - FytAt ,

Th

(6.10.3.3.2-1)

Ngc li: Dcp = D

trong :

D = chiu cao bn bng (mm)

At = din tch bn cnh chu ko (mm2)

Ac = din tch bn cnh chu nn (mm2)

Aw = din tch bn bng (mm2)

Fyc = cng chy do nh nht c quy nh ca bn cnh chu nn (MPa)

Fyt= cng chy nh nht c quy nh ca bn cnh chu ko (MPa)

Fyw = cng chy nh nht c quy nh ca bn bng (MPa)

6.10.3.4. cng

C th dng cc c trng v cng sau y phn tch cc cu kin chu un:

i vi ti trng tc dng ln cc mt ct khng lin hp: cc dc trng v cng ca mt ct thp.

i vi cc ti trng thng xuyn tc dng ln cc mt ct lin hp: cc c trng v cng ca mt ct lin hp di hn vi gi thit l mt cu b tng lm vic hon ton trn ton b nhp.

i vi cc ti trng nht thi tc dng ln cc mt ct lin hp: cc c trng v cng ca mt ct lin hp ngn hn vi gi thit l mt cu b tng lm vic hon ton trn ton b nhp.

6.10.3.5. Tc dng ca gi ln cc bn cnh dm

6.10.3.5.1. Cc mt ct c

M men tnh ton ca bn cnh di do tc dng gi ngang phi c gi thit s do mt b rng bw mi cnh ca bn cnh chu tnh theo cng thc:

(6.10.3.5.1-1)

trong :

bfb = Chiu rng cnh di (mm)

tfb = B dy bn cnh di (mm)

Fyb = Cng chy do nh nht c quy nh ca bn cnh di (MPa)

Mw = M men ngang ln nht bn cnh di do ti trng gi tnh ton (N-mm)

Cc ti trng thng ng trong t hp ti trng c nghin cu phi c gi thit s do mt ct lin hp hu ch chu. Mt ct ny c xc nh bng cch b bt b rng bw mi cnh mp ca bn cnh di. Phi cn c vo mt ct hu ch ny xc nh mi sc khng cn thit.

6.10.3.5.2 . Cc mt ct khng c

Cc ng sut bn cnh di ca cc mt ct khng c phi c t hp nh sau:

(6.10.3.5.2-1)

vi Fw = (6.10.3.5.2-2)

trong :

Fw = ng sut un cc cnh mp ca bn cnh di do tc dng ca lc gi tnh ton (MPa)

Fu = ng sut un bn cnh di do tc dng ca cc ti trng tnh ton khc ngoi tr ti trng gi (MPa)

Fr = sc khng un tnh ton ca mi bn cnh c quy nh trong iu 6.10.4 (MPa)

Mw = m men ngang ln nht bn cnh di do tc dng ca lc gi tnh ton (N-mm)Khng yu cu phi nghin cu i vi bn cnh trn. Nu sc khng un danh nh ca bn cnh trn c tnh ton theo cc quy nh iu 6.10.4.2.3 th phi s dng mt ct hu ch c quy nh iu 6.10.4.5.1 trong cc tnh ton .

6.10.3.6. Mt ct thc

Trong cc cu kin un c th b qua cc l bt bu lng cng cao hoc cc l m ( h) c ng knh khng qu 32mm min l din tch b khuyt i mi bn cnh khng vt qu 15% din tch ca bn cnh . i vi mi din tch b khuyt bn cnh vt qu 15% din tch bn cnh, phi tr chng ra khi mt ct th. Chiu rng cc l bu lng phi theo quy nh trong iu 6.8.3.

i vi vt liu mi ni, phi p dng cc quy nh ca cc iu6.8.1 v 6.13.5.

6.10.3.7. Ct thp ti thiu cc bn chu un m

Trong cc min chu un m ca bt k nhp lin tc no, tng din tch mt ct ngang ca ct thp dc phi khng nh hn 1% tng din tch mt ct ngang ca bn. Ct thp dng tho mn yu cu ny phi c cng chy do nh nht c quy nh khng nh hn 420 Mpa v c c khng ln hn cc thanh No. 19.

Phi b tr ct thp cn thit lm hai lp phn b u trn sut b rng bn v hai phn ba s lng phi c t lp trn. cc thanh ct thp phi t cch nhau khng qu 150mm trong mi hng.

C th dng cc b phn lin kt chng ct cc min chu un m ca cc mt ct lin hp. Khi b trng cc lin kt chng ct min chu un m th thng thng tt c cc ct dc phi c ko di vo n min chu un dng v vt ra ngoi cc lin kt chng ct mt khong cch khng nh hn chiu di khai trin c quy nh Phn 5.

6.10.4. Sc khng un theo trng thi gii hn cng

Sc khng un tnh ton i vi m men v ng sut phi c ly nh sau:

(6.10.4-1)

v Fr = (f Fn(6.10.4-2)

trong :

(f = h s khng un c quy nh iu 6.5.4.2

Mn = sc khng un danh nh (N-mm)

Fn = sc khng un danh nh mi bn cnh (MPa)

Cc quy nh v phn phi li m men ca iu 6.10.4.4 khng c p dng cho cc cu kin chu un nhp n.

i vi cc cu kin chu un c nhp lin tc, c th dng cc quy nh v n hi iu 6.10.4 hoc cc quy nh khng n hi iu 6.10.10 nghin cu trng thi gii hn cng . Ch i vi cc cu kin lin hp hoc khng lin hp vi mt ct c chiu cao khng i, c cc mt ct c c chng bn trong v c cng chy do nh nht m bo quy nh khng vt qu 345 Mpa mi iu kin cho php phn tch theo phng php khng n hi c ch dn iu 6.10.10.

6.10.4.1. Phn loi sc khng un

6.10.4.1.1. Cng chy do nh nht quy nh

Nghin cu v sc khng un ca cc mt ct ch tho mn cc gii hn v t l hnh hc trong iu 6.10.2 v nghin cu v vt liu thp c cng chy do nh nht quy nh nh sau:

Khng vt qu 345 MPa v c chiu cao mt ct khng i phi c thc hin theo cc quy nh v mnh ca bn bn bng c mt ct c ca iu 6.10.4.1.2, hoc

Vt qu 345 MPa v c chiu cao mt ct thay i phi c thc hin theo cc quy nh v mnh ca bn cnh chu nn c mt ct khng c ca iu 6.10.4.1.4.

6.10.4.1.1. mnh ca bn bn bng c mt ct c

Nu:

(6.10.4.1.2-1)

trong :

Dcp = chiu cao ca bn bn bng chu nn ti lc m men do (mm)

Fyc = cng chy do nh nht c quy nh ca bn cnh chu nn (MPa)th bn bng c xem l c v

i vi cc mt ct lin hp chu un dng sc khng un phi c xc nh theo cc quy nh ca iu 6.10.4.2.2 v sc khng un dng ca mt ct lin hp c hoc

i vi cc mt ct khc, vic nghin cu phi tin hnh theo cc quy nh ca iu 6.10.4.1.3 v mnh ca bn cnh chi ko c mt ct c.

Nu khc i th bn bn bng khng iu kin coi l c v

Nu khng s dng cng thc Q th:

i vi cc mt ct lin hp chu un dng, phi xc nh sc khng un ca mi bn cnh theo cc quy nh ca iu 6.10.4.2.4 v sc khng un ca bn cnh c mt ct khng c, hoc

i vi cc ct khc, phi tin hnh nghin cu theo cc quy nh ca iu 6.10.4.1.4 v mnh ca bn cnh chu nn c mt ct khng c hoc :

Nu s dng cng t